diff --git a/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.spec.ts b/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.spec.ts
index d7fbb79a..fd50ce79 100644
--- a/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.spec.ts
+++ b/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.spec.ts
@@ -335,4 +335,28 @@ describe("<fui-sms-multi-factor-assertion-verify-form>", () => {
       expect(onSuccessSpy).toHaveBeenCalled();
     });
   });
+
+  it("emits onSuccess with credential after successful verification", async () => {
+    const mockCredential = { user: { uid: "sms-verify-user" } };
+    signInWithMultiFactorAssertion.mockResolvedValue(mockCredential);
+
+    const { fixture } = await render(SmsMultiFactorAssertionVerifyFormComponent, {
+      componentInputs: {
+        verificationId: "test-verification-id",
+      },
+      imports: [SmsMultiFactorAssertionVerifyFormComponent],
+    });
+
+    const onSuccessSpy = jest.fn();
+    fixture.componentInstance.onSuccess.subscribe(onSuccessSpy);
+
+    const component = fixture.componentInstance;
+    component.form.setFieldValue("verificationCode", "123456");
+    component.form.setFieldValue("verificationId", "test-verification-id");
+    await component.form.handleSubmit();
+
+    await waitFor(() => {
+      expect(onSuccessSpy).toHaveBeenCalledWith(mockCredential);
+    });
+  });
 });
diff --git a/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.ts b/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.ts
index 8256dd57..9e84f047 100644
--- a/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.ts
+++ b/packages/angular/src/lib/auth/forms/mfa/sms-multi-factor-assertion-form.ts
@@ -23,10 +23,9 @@ import {
   injectTranslation,
   injectUI,
 } from "../../../provider";
-import { RecaptchaVerifier } from "@angular/fire/auth";
 import { FormInputComponent, FormSubmitComponent, FormErrorMessageComponent } from "../../../components/form";
 import { FirebaseUIError, verifyPhoneNumber, signInWithMultiFactorAssertion } from "@firebase-ui/core";
-import { PhoneAuthProvider, PhoneMultiFactorGenerator, type MultiFactorInfo } from "firebase/auth";
+import { PhoneAuthProvider, PhoneMultiFactorGenerator, type UserCredential, type MultiFactorInfo } from "firebase/auth";
 
 type PhoneMultiFactorInfo = MultiFactorInfo & {
   phoneNumber?: string;
@@ -179,7 +178,7 @@ export class SmsMultiFactorAssertionVerifyFormComponent {
   private formSchema = injectMultiFactorPhoneAuthVerifyFormSchema();
 
   verificationId = input.required<string>();
-  onSuccess = output<void>();
+  onSuccess = output<UserCredential>();
 
   verificationCodeLabel = injectTranslation("labels", "verificationCode");
   verifyCodeLabel = injectTranslation("labels", "verifyCode");
@@ -208,8 +207,8 @@ export class SmsMultiFactorAssertionVerifyFormComponent {
             try {
               const credential = PhoneAuthProvider.credential(value.verificationId, value.verificationCode);
               const assertion = PhoneMultiFactorGenerator.assertion(credential);
-              await signInWithMultiFactorAssertion(this.ui(), assertion);
-              this.onSuccess.emit();
+              const result = await signInWithMultiFactorAssertion(this.ui(), assertion);
+              this.onSuccess.emit(result);
               return;
             } catch (error) {
               if (error instanceof FirebaseUIError) {
@@ -239,7 +238,7 @@ export class SmsMultiFactorAssertionVerifyFormComponent {
       @if (verification()) {
         <fui-sms-multi-factor-assertion-verify-form
           [verificationId]="verification()!.verificationId"
-          (onSuccess)="onSuccess.emit()"
+          (onSuccess)="onSuccess.emit($event)"
         />
       } @else {
         <fui-sms-multi-factor-assertion-phone-form [hint]="hint()" (onSubmit)="handlePhoneSubmit($event)" />
@@ -249,7 +248,7 @@ export class SmsMultiFactorAssertionVerifyFormComponent {
 })
 export class SmsMultiFactorAssertionFormComponent {
   hint = input.required<MultiFactorInfo>();
-  onSuccess = output<void>();
+  onSuccess = output<UserCredential>();
 
   verification = signal<{ verificationId: string } | null>(null);
 
diff --git a/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.spec.ts b/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.spec.ts
index ec780ba0..bf3abfae 100644
--- a/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.spec.ts
+++ b/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.spec.ts
@@ -145,6 +145,36 @@ describe("<fui-totp-multi-factor-assertion-form>", () => {
     });
   });
 
+  it("emits onSuccess with credential after successful verification", async () => {
+    const mockHint = {
+      factorId: TotpMultiFactorGenerator.FACTOR_ID,
+      displayName: "TOTP",
+      uid: "test-uid",
+    };
+
+    const mockCredential = { user: { uid: "totp-verify-user" } };
+    signInWithMultiFactorAssertion.mockResolvedValue(mockCredential);
+
+    const { fixture } = await render(TotpMultiFactorAssertionFormComponent, {
+      componentInputs: {
+        hint: mockHint,
+      },
+      imports: [TotpMultiFactorAssertionFormComponent],
+    });
+
+    const component = fixture.componentInstance;
+    const onSuccessSpy = jest.fn();
+    component.onSuccess.subscribe(onSuccessSpy);
+
+    component.form.setFieldValue("verificationCode", "123456");
+    fixture.detectChanges();
+
+    await component.form.handleSubmit();
+    await waitFor(() => {
+      expect(onSuccessSpy).toHaveBeenCalledWith(mockCredential);
+    });
+  });
+
   it("calls TotpMultiFactorGenerator.assertionForSignIn with correct parameters", async () => {
     const mockHint = {
       factorId: TotpMultiFactorGenerator.FACTOR_ID,
diff --git a/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.ts b/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.ts
index 6e479bf8..307d8f53 100644
--- a/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.ts
+++ b/packages/angular/src/lib/auth/forms/mfa/totp-multi-factor-assertion-form.ts
@@ -19,7 +19,7 @@ import { injectForm, injectStore, TanStackAppField, TanStackField } from "@tanst
 import { injectMultiFactorTotpAuthVerifyFormSchema, injectTranslation, injectUI } from "../../../provider";
 import { FormInputComponent, FormSubmitComponent, FormErrorMessageComponent } from "../../../components/form";
 import { FirebaseUIError, signInWithMultiFactorAssertion } from "@firebase-ui/core";
-import { TotpMultiFactorGenerator, type MultiFactorInfo } from "firebase/auth";
+import { TotpMultiFactorGenerator, type UserCredential, type MultiFactorInfo } from "firebase/auth";
 
 @Component({
   selector: "fui-totp-multi-factor-assertion-form",
@@ -59,7 +59,7 @@ export class TotpMultiFactorAssertionFormComponent {
   private formSchema = injectMultiFactorTotpAuthVerifyFormSchema();
 
   hint = input.required<MultiFactorInfo>();
-  onSuccess = output<void>();
+  onSuccess = output<UserCredential>();
 
   verificationCodeLabel = injectTranslation("labels", "verificationCode");
   verifyCodeLabel = injectTranslation("labels", "verifyCode");
@@ -82,8 +82,8 @@ export class TotpMultiFactorAssertionFormComponent {
           onSubmitAsync: async ({ value }) => {
             try {
               const assertion = TotpMultiFactorGenerator.assertionForSignIn(this.hint().uid, value.verificationCode);
-              await signInWithMultiFactorAssertion(this.ui(), assertion);
-              this.onSuccess.emit();
+              const result = await signInWithMultiFactorAssertion(this.ui(), assertion);
+              this.onSuccess.emit(result);
               return;
             } catch (error) {
               if (error instanceof FirebaseUIError) {
diff --git a/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.spec.ts b/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.spec.ts
index 6be6e6bf..6792439e 100644
--- a/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.spec.ts
+++ b/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.spec.ts
@@ -136,7 +136,7 @@ describe("<fui-multi-factor-auth-assertion-form>", () => {
     expect(screen.queryByRole("button", { name: "SMS Verification" })).not.toBeInTheDocument();
   });
 
-  it("throws error when no resolver is provided", () => {
+  it("throws error when no resolver is provided", async () => {
     const { injectUI } = require("../../../provider");
     injectUI.mockImplementation(() => {
       return () => ({
@@ -144,8 +144,10 @@ describe("<fui-multi-factor-auth-assertion-form>", () => {
       });
     });
 
-    expect(() => {
-      new MultiFactorAuthAssertionFormComponent();
-    }).toThrow("MultiFactorAuthAssertionForm requires a multi-factor resolver");
+    await expect(
+      render(MultiFactorAuthAssertionFormComponent, {
+        imports: [MultiFactorAuthAssertionFormComponent],
+      })
+    ).rejects.toThrow("MultiFactorAuthAssertionForm requires a multi-factor resolver");
   });
 });
diff --git a/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.ts b/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.ts
index 848f7c7c..0c76e925 100644
--- a/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.ts
+++ b/packages/angular/src/lib/auth/forms/multi-factor-auth-assertion-form.ts
@@ -14,10 +14,15 @@
  * limitations under the License.
  */
 
-import { Component, computed, signal } from "@angular/core";
+import { Component, computed, output, signal } from "@angular/core";
 import { CommonModule } from "@angular/common";
 import { injectUI, injectTranslation } from "../../provider";
-import { PhoneMultiFactorGenerator, TotpMultiFactorGenerator, type MultiFactorInfo } from "firebase/auth";
+import {
+  PhoneMultiFactorGenerator,
+  TotpMultiFactorGenerator,
+  type UserCredential,
+  type MultiFactorInfo,
+} from "firebase/auth";
 import { SmsMultiFactorAssertionFormComponent } from "./mfa/sms-multi-factor-assertion-form";
 import { TotpMultiFactorAssertionFormComponent } from "./mfa/totp-multi-factor-assertion-form";
 import { ButtonComponent } from "../../components/button";
@@ -30,9 +35,9 @@ import { ButtonComponent } from "../../components/button";
     <div class="fui-content">
       @if (selectedHint()) {
         @if (selectedHint()!.factorId === phoneFactorId()) {
-          <fui-sms-multi-factor-assertion-form [hint]="selectedHint()!" />
+          <fui-sms-multi-factor-assertion-form [hint]="selectedHint()!" (onSuccess)="onSuccess.emit($event)" />
         } @else if (selectedHint()!.factorId === totpFactorId()) {
-          <fui-totp-multi-factor-assertion-form [hint]="selectedHint()!" />
+          <fui-totp-multi-factor-assertion-form [hint]="selectedHint()!" (onSuccess)="onSuccess.emit($event)" />
         }
       } @else {
         <p>TODO: Select a multi-factor authentication method</p>
@@ -54,6 +59,8 @@ import { ButtonComponent } from "../../components/button";
 export class MultiFactorAuthAssertionFormComponent {
   private ui = injectUI();
 
+  onSuccess = output<UserCredential>();
+
   resolver = computed(() => {
     const resolver = this.ui().multiFactorResolver;
     if (!resolver) {
diff --git a/packages/angular/src/lib/auth/screens/oauth-screen.spec.ts b/packages/angular/src/lib/auth/screens/oauth-screen.spec.ts
index e9b2d4ac..49a57e09 100644
--- a/packages/angular/src/lib/auth/screens/oauth-screen.spec.ts
+++ b/packages/angular/src/lib/auth/screens/oauth-screen.spec.ts
@@ -15,7 +15,7 @@
  */
 
 import { render, screen } from "@testing-library/angular";
-import { Component } from "@angular/core";
+import { Component, EventEmitter } from "@angular/core";
 import { TestBed } from "@angular/core/testing";
 
 import { OAuthScreenComponent } from "./oauth-screen";
@@ -50,13 +50,6 @@ class MockPoliciesComponent {}
 })
 class MockRedirectErrorComponent {}
 
-@Component({
-  selector: "fui-multi-factor-auth-assertion-form",
-  template: '<div data-testid="mfa-assertion-form">MFA Assertion Form</div>',
-  standalone: true,
-})
-class MockMultiFactorAuthAssertionFormComponent {}
-
 @Component({
   template: `
     <fui-oauth-screen>
@@ -87,6 +80,15 @@ class TestHostWithMultipleProvidersComponent {}
 })
 class TestHostWithoutContentComponent {}
 
+@Component({
+  selector: "fui-multi-factor-auth-assertion-form",
+  template: '<div data-testid="mfa-assertion-form">MFA Assertion Form</div>',
+  standalone: true,
+})
+class MockMultiFactorAuthAssertionFormComponent {
+  onSuccess = new EventEmitter();
+}
+
 describe("<fui-oauth-screen>", () => {
   beforeEach(() => {
     const { injectTranslation, injectPolicies, injectRedirectError, injectUI } = require("../../../provider");
@@ -124,7 +126,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -144,7 +146,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -164,7 +166,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -185,7 +187,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -210,7 +212,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -230,7 +232,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -255,7 +257,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -288,7 +290,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -321,7 +323,7 @@ describe("<fui-oauth-screen>", () => {
         OAuthScreenComponent,
         MockPoliciesComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -334,4 +336,54 @@ describe("<fui-oauth-screen>", () => {
     expect(screen.queryByTestId("policies")).not.toBeInTheDocument();
     expect(screen.getByTestId("mfa-assertion-form")).toBeInTheDocument();
   });
+
+  it("emits onSignIn with credential when MFA flow succeeds", async () => {
+    const { injectUI } = require("../../../provider");
+    injectUI.mockImplementation(() => {
+      return () => ({
+        multiFactorResolver: { hints: [{ factorId: "totp", uid: "test" }] },
+      });
+    });
+
+    TestBed.overrideComponent(MultiFactorAuthAssertionFormComponent, {
+      set: {
+        template:
+          '<div data-testid="mfa-assertion-form">MFA Assertion Form</div><button data-testid="mfa-on-success" (click)="onSuccess.emit({ user: { uid: \'angular-oauth-mfa-user\' } })">Trigger</button>',
+      },
+    });
+
+    const onSignInHandler = jest.fn();
+
+    @Component({
+      template: `<fui-oauth-screen (onSignIn)="onSignIn($event)"></fui-oauth-screen>`,
+      standalone: true,
+      imports: [OAuthScreenComponent],
+    })
+    class HostCaptureComponent {
+      onSignIn = onSignInHandler;
+    }
+
+    await render(HostCaptureComponent, {
+      imports: [
+        OAuthScreenComponent,
+        MockPoliciesComponent,
+        MockRedirectErrorComponent,
+        MultiFactorAuthAssertionFormComponent,
+        CardComponent,
+        CardHeaderComponent,
+        CardTitleComponent,
+        CardSubtitleComponent,
+        CardContentComponent,
+        ContentComponent,
+      ],
+    });
+
+    const trigger = screen.getByTestId("mfa-on-success");
+    trigger.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+
+    expect(onSignInHandler).toHaveBeenCalled();
+    expect(onSignInHandler).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "angular-oauth-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/angular/src/lib/auth/screens/oauth-screen.ts b/packages/angular/src/lib/auth/screens/oauth-screen.ts
index 14d60dd0..04b4e279 100644
--- a/packages/angular/src/lib/auth/screens/oauth-screen.ts
+++ b/packages/angular/src/lib/auth/screens/oauth-screen.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Component, computed } from "@angular/core";
+import { Component, computed, output } from "@angular/core";
 import { CommonModule } from "@angular/common";
 import {
   CardComponent,
@@ -28,6 +28,7 @@ import { PoliciesComponent } from "../../components/policies";
 import { ContentComponent } from "../../components/content";
 import { MultiFactorAuthAssertionFormComponent } from "../forms/multi-factor-auth-assertion-form";
 import { RedirectErrorComponent } from "../../components/redirect-error";
+import { type UserCredential } from "firebase/auth";
 
 @Component({
   selector: "fui-oauth-screen",
@@ -53,7 +54,7 @@ import { RedirectErrorComponent } from "../../components/redirect-error";
         </fui-card-header>
         <fui-card-content>
           @if (mfaResolver()) {
-            <fui-multi-factor-auth-assertion-form />
+            <fui-multi-factor-auth-assertion-form (onSuccess)="onSignIn.emit($event)" />
           } @else {
             <fui-content>
               <ng-content></ng-content>
@@ -73,4 +74,6 @@ export class OAuthScreenComponent {
 
   titleText = injectTranslation("labels", "signIn");
   subtitleText = injectTranslation("prompts", "signInToAccount");
+
+  onSignIn = output<UserCredential>();
 }
diff --git a/packages/angular/src/lib/auth/screens/phone-auth-screen.spec.ts b/packages/angular/src/lib/auth/screens/phone-auth-screen.spec.ts
index 11844a59..45b93772 100644
--- a/packages/angular/src/lib/auth/screens/phone-auth-screen.spec.ts
+++ b/packages/angular/src/lib/auth/screens/phone-auth-screen.spec.ts
@@ -27,6 +27,8 @@ import {
   CardContentComponent,
 } from "../../components/card";
 import { MultiFactorAuthAssertionFormComponent } from "../forms/multi-factor-auth-assertion-form";
+import { TotpMultiFactorAssertionFormComponent } from "../forms/mfa/totp-multi-factor-assertion-form";
+import { TotpMultiFactorGenerator } from "firebase/auth";
 
 @Component({
   selector: "fui-phone-auth-form",
@@ -42,13 +44,6 @@ class MockPhoneAuthFormComponent {}
 })
 class MockRedirectErrorComponent {}
 
-@Component({
-  selector: "fui-multi-factor-auth-assertion-form",
-  template: '<div data-testid="mfa-assertion-form">MFA Assertion Form</div>',
-  standalone: true,
-})
-class MockMultiFactorAuthAssertionFormComponent {}
-
 @Component({
   template: `
     <fui-phone-auth-screen>
@@ -95,7 +90,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -114,7 +109,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -134,7 +129,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -154,7 +149,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -173,7 +168,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -197,7 +192,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -229,7 +224,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -261,7 +256,7 @@ describe("<fui-phone-auth-screen>", () => {
         PhoneAuthScreenComponent,
         MockPhoneAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -273,4 +268,53 @@ describe("<fui-phone-auth-screen>", () => {
     expect(screen.queryByText("Phone Auth Form")).not.toBeInTheDocument();
     expect(screen.getByTestId("mfa-assertion-form")).toBeInTheDocument();
   });
+
+  it("emits signIn with credential when MFA flow succeeds", async () => {
+    const { injectUI } = require("../../../provider");
+    injectUI.mockImplementation(() => {
+      return () => ({
+        multiFactorResolver: { hints: [{ factorId: TotpMultiFactorGenerator.FACTOR_ID, uid: "test" }] },
+      });
+    });
+
+    TestBed.overrideComponent(TotpMultiFactorAssertionFormComponent, {
+      set: {
+        template:
+          '<div data-testid="totp-assertion-form">TOTP</div><button data-testid="mfa-on-success" (click)="onSuccess.emit({ user: { uid: \'angular-phone-mfa-user\' } })">Trigger</button>',
+      },
+    });
+
+    const signInHandler = jest.fn();
+
+    @Component({
+      template: `<fui-phone-auth-screen (signIn)="onSignIn($event)"></fui-phone-auth-screen>`,
+      standalone: true,
+      imports: [PhoneAuthScreenComponent],
+    })
+    class HostCaptureComponent {
+      onSignIn = signInHandler;
+    }
+
+    await render(HostCaptureComponent, {
+      imports: [
+        PhoneAuthScreenComponent,
+        MockPhoneAuthFormComponent,
+        MockRedirectErrorComponent,
+        MultiFactorAuthAssertionFormComponent, // Using real component
+        CardComponent,
+        CardHeaderComponent,
+        CardTitleComponent,
+        CardSubtitleComponent,
+        CardContentComponent,
+      ],
+    });
+
+    const trigger = screen.getByTestId("mfa-on-success");
+    trigger.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+
+    expect(signInHandler).toHaveBeenCalled();
+    expect(signInHandler).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "angular-phone-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/angular/src/lib/auth/screens/phone-auth-screen.ts b/packages/angular/src/lib/auth/screens/phone-auth-screen.ts
index 8c3f692e..fb12e057 100644
--- a/packages/angular/src/lib/auth/screens/phone-auth-screen.ts
+++ b/packages/angular/src/lib/auth/screens/phone-auth-screen.ts
@@ -52,7 +52,7 @@ import { UserCredential } from "@angular/fire/auth";
         </fui-card-header>
         <fui-card-content>
           @if (mfaResolver()) {
-            <fui-multi-factor-auth-assertion-form />
+            <fui-multi-factor-auth-assertion-form (onSuccess)="signIn.emit($event)" />
           } @else {
             <fui-phone-auth-form (signIn)="signIn.emit($event)" />
             <fui-redirect-error />
diff --git a/packages/angular/src/lib/auth/screens/sign-in-auth-screen.spec.ts b/packages/angular/src/lib/auth/screens/sign-in-auth-screen.spec.ts
index 2e2361a1..d87a65e6 100644
--- a/packages/angular/src/lib/auth/screens/sign-in-auth-screen.spec.ts
+++ b/packages/angular/src/lib/auth/screens/sign-in-auth-screen.spec.ts
@@ -27,6 +27,8 @@ import {
   CardContentComponent,
 } from "../../components/card";
 import { MultiFactorAuthAssertionFormComponent } from "../forms/multi-factor-auth-assertion-form";
+import { TotpMultiFactorAssertionFormComponent } from "../forms/mfa/totp-multi-factor-assertion-form";
+import { TotpMultiFactorGenerator } from "firebase/auth";
 
 @Component({
   selector: "fui-sign-in-auth-form",
@@ -42,13 +44,6 @@ class MockSignInAuthFormComponent {}
 })
 class MockRedirectErrorComponent {}
 
-@Component({
-  selector: "fui-multi-factor-auth-assertion-form",
-  template: '<div data-testid="mfa-assertion-form">MFA Assertion Form</div>',
-  standalone: true,
-})
-class MockMultiFactorAuthAssertionFormComponent {}
-
 @Component({
   template: `
     <fui-sign-in-auth-screen>
@@ -95,7 +90,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -114,7 +109,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -134,7 +129,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -154,7 +149,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -173,7 +168,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -197,7 +192,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -229,7 +224,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -261,7 +256,7 @@ describe("<fui-sign-in-auth-screen>", () => {
         SignInAuthScreenComponent,
         MockSignInAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -273,4 +268,53 @@ describe("<fui-sign-in-auth-screen>", () => {
     expect(screen.queryByRole("button", { name: "Sign in" })).not.toBeInTheDocument();
     expect(screen.getByTestId("mfa-assertion-form")).toBeInTheDocument();
   });
+
+  it("emits signIn with credential when MFA flow succeeds", async () => {
+    const { injectUI } = require("../../../provider");
+    injectUI.mockImplementation(() => {
+      return () => ({
+        multiFactorResolver: { hints: [{ factorId: TotpMultiFactorGenerator.FACTOR_ID, uid: "test" }] },
+      });
+    });
+
+    TestBed.overrideComponent(TotpMultiFactorAssertionFormComponent, {
+      set: {
+        template:
+          '<div data-testid="totp-assertion-form">TOTP</div><button data-testid="mfa-on-success" (click)="onSuccess.emit({ user: { uid: \'angular-mfa-user\' } })">Trigger</button>',
+      },
+    });
+
+    const signInHandler = jest.fn();
+
+    @Component({
+      template: `<fui-sign-in-auth-screen (signIn)="onSignIn($event)"></fui-sign-in-auth-screen>`,
+      standalone: true,
+      imports: [SignInAuthScreenComponent],
+    })
+    class HostCaptureComponent {
+      onSignIn = signInHandler;
+    }
+
+    await render(HostCaptureComponent, {
+      imports: [
+        SignInAuthScreenComponent,
+        MockSignInAuthFormComponent,
+        MockRedirectErrorComponent,
+        MultiFactorAuthAssertionFormComponent,
+        CardComponent,
+        CardHeaderComponent,
+        CardTitleComponent,
+        CardSubtitleComponent,
+        CardContentComponent,
+      ],
+    });
+
+    const trigger = screen.getByTestId("mfa-on-success");
+    trigger.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+
+    expect(signInHandler).toHaveBeenCalled();
+    expect(signInHandler).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "angular-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/angular/src/lib/auth/screens/sign-in-auth-screen.ts b/packages/angular/src/lib/auth/screens/sign-in-auth-screen.ts
index 7ff81dee..abf25481 100644
--- a/packages/angular/src/lib/auth/screens/sign-in-auth-screen.ts
+++ b/packages/angular/src/lib/auth/screens/sign-in-auth-screen.ts
@@ -52,7 +52,7 @@ import { UserCredential } from "@angular/fire/auth";
         </fui-card-header>
         <fui-card-content>
           @if (mfaResolver()) {
-            <fui-multi-factor-auth-assertion-form />
+            <fui-multi-factor-auth-assertion-form (onSuccess)="signIn.emit($event)" />
           } @else {
             <fui-sign-in-auth-form
               (forgotPassword)="forgotPassword.emit()"
diff --git a/packages/angular/src/lib/auth/screens/sign-up-auth-screen.spec.ts b/packages/angular/src/lib/auth/screens/sign-up-auth-screen.spec.ts
index a456fca7..f7879f31 100644
--- a/packages/angular/src/lib/auth/screens/sign-up-auth-screen.spec.ts
+++ b/packages/angular/src/lib/auth/screens/sign-up-auth-screen.spec.ts
@@ -27,6 +27,8 @@ import {
   CardContentComponent,
 } from "../../components/card";
 import { MultiFactorAuthAssertionFormComponent } from "../forms/multi-factor-auth-assertion-form";
+import { TotpMultiFactorAssertionFormComponent } from "../forms/mfa/totp-multi-factor-assertion-form";
+import { TotpMultiFactorGenerator } from "firebase/auth";
 
 @Component({
   selector: "fui-sign-up-auth-form",
@@ -42,13 +44,6 @@ class MockSignUpAuthFormComponent {}
 })
 class MockRedirectErrorComponent {}
 
-@Component({
-  selector: "fui-multi-factor-auth-assertion-form",
-  template: '<div data-testid="mfa-assertion-form">MFA Assertion Form</div>',
-  standalone: true,
-})
-class MockMultiFactorAuthAssertionFormComponent {}
-
 @Component({
   template: `
     <fui-sign-up-auth-screen>
@@ -95,7 +90,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -114,7 +109,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -133,7 +128,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -153,7 +148,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -172,7 +167,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -196,7 +191,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -228,7 +223,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -260,7 +255,7 @@ describe("<fui-sign-up-auth-screen>", () => {
         SignUpAuthScreenComponent,
         MockSignUpAuthFormComponent,
         MockRedirectErrorComponent,
-        MockMultiFactorAuthAssertionFormComponent,
+        MultiFactorAuthAssertionFormComponent,
         CardComponent,
         CardHeaderComponent,
         CardTitleComponent,
@@ -272,4 +267,53 @@ describe("<fui-sign-up-auth-screen>", () => {
     expect(screen.queryByText("Sign Up Form")).not.toBeInTheDocument();
     expect(screen.getByTestId("mfa-assertion-form")).toBeInTheDocument();
   });
+
+  it("emits signUp with credential when MFA flow succeeds", async () => {
+    const { injectUI } = require("../../../provider");
+    injectUI.mockImplementation(() => {
+      return () => ({
+        multiFactorResolver: { hints: [{ factorId: TotpMultiFactorGenerator.FACTOR_ID, uid: "test" }] },
+      });
+    });
+
+    TestBed.overrideComponent(TotpMultiFactorAssertionFormComponent, {
+      set: {
+        template:
+          '<div data-testid="totp-assertion-form">TOTP</div><button data-testid="mfa-on-success" (click)="onSuccess.emit({ user: { uid: \'angular-signup-mfa-user\' } })">Trigger</button>',
+      },
+    });
+
+    const signUpHandler = jest.fn();
+
+    @Component({
+      template: `<fui-sign-up-auth-screen (signUp)="onSignUp($event)"></fui-sign-up-auth-screen>`,
+      standalone: true,
+      imports: [SignUpAuthScreenComponent],
+    })
+    class HostCaptureComponent {
+      onSignUp = signUpHandler;
+    }
+
+    await render(HostCaptureComponent, {
+      imports: [
+        SignUpAuthScreenComponent,
+        MockSignUpAuthFormComponent,
+        MockRedirectErrorComponent,
+        MultiFactorAuthAssertionFormComponent,
+        CardComponent,
+        CardHeaderComponent,
+        CardTitleComponent,
+        CardSubtitleComponent,
+        CardContentComponent,
+      ],
+    });
+
+    const trigger = screen.getByTestId("mfa-on-success");
+    trigger.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+
+    expect(signUpHandler).toHaveBeenCalled();
+    expect(signUpHandler).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "angular-signup-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/angular/src/lib/auth/screens/sign-up-auth-screen.ts b/packages/angular/src/lib/auth/screens/sign-up-auth-screen.ts
index 53da6747..ce206f4a 100644
--- a/packages/angular/src/lib/auth/screens/sign-up-auth-screen.ts
+++ b/packages/angular/src/lib/auth/screens/sign-up-auth-screen.ts
@@ -53,7 +53,7 @@ import {
         </fui-card-header>
         <fui-card-content>
           @if (mfaResolver()) {
-            <fui-multi-factor-auth-assertion-form />
+            <fui-multi-factor-auth-assertion-form (onSuccess)="signUp.emit($event)" />
           } @else {
             <fui-sign-up-auth-form (signIn)="signIn.emit()" (signUp)="signUp.emit($event)" />
             <fui-redirect-error />
diff --git a/packages/core/src/auth.test.ts b/packages/core/src/auth.test.ts
index 99670a2f..c1175bbd 100644
--- a/packages/core/src/auth.test.ts
+++ b/packages/core/src/auth.test.ts
@@ -12,6 +12,7 @@ import {
   signInWithProvider,
   signInWithCustomToken,
   generateTotpQrCode,
+  signInWithMultiFactorAssertion,
 } from "./auth";
 
 vi.mock("firebase/auth", () => ({
@@ -42,7 +43,6 @@ vi.mock("./errors", () => ({
   handleFirebaseError: vi.fn(),
 }));
 
-// Import the mocked functions
 import {
   signInWithCredential as _signInWithCredential,
   EmailAuthProvider,
@@ -85,13 +85,11 @@ describe("signInWithEmailAndPassword", () => {
 
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
 
-    // Calls pending pre-_signInWithCredential call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
 
     expect(_signInWithCredential).toHaveBeenCalledWith(mockUI.auth, credential);
     expect(_signInWithCredential).toHaveBeenCalledTimes(1);
 
-    // Assert that the result is a valid UserCredential.
     expect(result.providerId).toBe("password");
   });
 
@@ -113,7 +111,6 @@ describe("signInWithEmailAndPassword", () => {
     expect(mockBehavior).toHaveBeenCalledWith(mockUI, credential);
     expect(result.providerId).toBe("password");
 
-    // Auth method sets pending at start, then idle in finally block.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -137,7 +134,6 @@ describe("signInWithEmailAndPassword", () => {
     expect(_signInWithCredential).toHaveBeenCalledWith(mockUI.auth, credential);
     expect(_signInWithCredential).toHaveBeenCalledTimes(1);
 
-    // Calls pending pre-_signInWithCredential call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -178,13 +174,11 @@ describe("createUserWithEmailAndPassword", () => {
 
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
 
-    // Calls pending pre-createUserWithEmailAndPassword call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
 
     expect(_createUserWithEmailAndPassword).toHaveBeenCalledWith(mockUI.auth, email, password);
     expect(_createUserWithEmailAndPassword).toHaveBeenCalledTimes(1);
 
-    // Assert that the result is a valid UserCredential.
     expect(result.providerId).toBe("password");
   });
 
@@ -210,7 +204,6 @@ describe("createUserWithEmailAndPassword", () => {
     expect(mockBehavior).toHaveBeenCalledWith(mockUI, credential);
     expect(result.providerId).toBe("password");
 
-    // Auth method sets pending at start, then idle in finally block.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -238,7 +231,6 @@ describe("createUserWithEmailAndPassword", () => {
     expect(_createUserWithEmailAndPassword).toHaveBeenCalledWith(mockUI.auth, email, password);
     expect(_createUserWithEmailAndPassword).toHaveBeenCalledTimes(1);
 
-    // Calls pending pre-createUserWithEmailAndPassword call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -400,15 +392,12 @@ describe("verifyPhoneNumber", () => {
 
     const result = await verifyPhoneNumber(mockUI, phoneNumber, mockAppVerifier);
 
-    // Verify state management
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
 
-    // Verify the PhoneAuthProvider was created and verifyPhoneNumber was called
     expect(PhoneAuthProvider).toHaveBeenCalledWith(mockUI.auth);
     expect(mockVerifyPhoneNumber).toHaveBeenCalledWith(phoneNumber, mockAppVerifier);
     expect(mockVerifyPhoneNumber).toHaveBeenCalledTimes(1);
 
-    // Verify the result
     expect(result).toEqual(mockVerificationId);
   });
 
@@ -605,6 +594,52 @@ describe("confirmPhoneNumber", () => {
   });
 });
 
+describe("signInWithMultiFactorAssertion", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("resolves sign-in via resolver, clears resolver, and returns credential", async () => {
+    const mockUI = createMockUI();
+
+    const mockCredential = { providerId: "mfa", user: { uid: "mfa-user" } } as UserCredential;
+    const resolveSignIn = vi.fn().mockResolvedValue(mockCredential);
+
+    const mockResolver = { resolveSignIn } as any;
+    (mockUI as any).multiFactorResolver = mockResolver;
+
+    const mockAssertion = { assertion: true } as any; // type MultiFactorAssertion
+
+    const result = await signInWithMultiFactorAssertion(mockUI, mockAssertion);
+
+    expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
+
+    expect(resolveSignIn).toHaveBeenCalledWith(mockAssertion);
+    expect(resolveSignIn).toHaveBeenCalledTimes(1);
+
+    expect(mockUI.setMultiFactorResolver).toHaveBeenCalledWith(undefined);
+
+    expect(result).toBe(mockCredential);
+  });
+
+  it("handles errors via handleFirebaseError and maintains state transitions", async () => {
+    const mockUI = createMockUI();
+
+    const error = new FirebaseError("auth/mfa-error", "MFA resolution failed");
+    const resolveSignIn = vi.fn().mockRejectedValue(error);
+    const mockResolver = { resolveSignIn } as any;
+    (mockUI as any).multiFactorResolver = mockResolver;
+
+    const mockAssertion = { assertion: true } as any; // type MultiFactorAssertion
+
+    await signInWithMultiFactorAssertion(mockUI, mockAssertion);
+
+    expect(handleFirebaseError).toHaveBeenCalledWith(mockUI, error);
+
+    expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
+  });
+});
+
 describe("sendPasswordResetEmail", () => {
   beforeEach(() => {
     vi.clearAllMocks();
@@ -618,10 +653,8 @@ describe("sendPasswordResetEmail", () => {
 
     await sendPasswordResetEmail(mockUI, email);
 
-    // Verify state management
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
 
-    // Verify the Firebase function was called with correct parameters
     expect(_sendPasswordResetEmail).toHaveBeenCalledWith(mockUI.auth, email);
     expect(_sendPasswordResetEmail).toHaveBeenCalledTimes(1);
   });
@@ -635,10 +668,8 @@ describe("sendPasswordResetEmail", () => {
 
     await sendPasswordResetEmail(mockUI, email);
 
-    // Verify error handling
     expect(handleFirebaseError).toHaveBeenCalledWith(mockUI, error);
 
-    // Verify state management still happens
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 });
@@ -646,7 +677,6 @@ describe("sendPasswordResetEmail", () => {
 describe("sendSignInLinkToEmail", () => {
   beforeEach(() => {
     vi.clearAllMocks();
-    // Mock window.location.href
     Object.defineProperty(window, "location", {
       value: { href: "https://example.com" },
       writable: true,
@@ -654,7 +684,6 @@ describe("sendSignInLinkToEmail", () => {
   });
 
   afterEach(() => {
-    // Clean up localStorage after each test
     window.localStorage.clear();
   });
 
@@ -675,7 +704,6 @@ describe("sendSignInLinkToEmail", () => {
     expect(_sendSignInLinkToEmail).toHaveBeenCalledWith(mockUI.auth, email, expectedActionCodeSettings);
     expect(_sendSignInLinkToEmail).toHaveBeenCalledTimes(1);
 
-    // Verify email is stored in localStorage
     expect(window.localStorage.getItem("emailForSignIn")).toBe(email);
   });
 
@@ -688,13 +716,10 @@ describe("sendSignInLinkToEmail", () => {
 
     await sendSignInLinkToEmail(mockUI, email);
 
-    // Verify error handling
     expect(handleFirebaseError).toHaveBeenCalledWith(mockUI, error);
 
-    // Verify state management still happens
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
 
-    // Verify email is NOT stored in localStorage on error
     expect(window.localStorage.getItem("emailForSignIn")).toBeNull();
   });
 
@@ -750,15 +775,12 @@ describe("signInWithEmailLink", () => {
 
     const result = await signInWithEmailLink(mockUI, email, link);
 
-    // Verify credential was created correctly
     expect(EmailAuthProvider.credentialWithLink).toHaveBeenCalledWith(email, link);
 
-    // Verify our signInWithCredential function was called (which internally calls Firebase)
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
     expect(_signInWithCredential).toHaveBeenCalledWith(mockUI.auth, credential);
     expect(_signInWithCredential).toHaveBeenCalledTimes(1);
 
-    // Assert that the result is a valid UserCredential.
     expect(result.providerId).toBe("emailLink");
   });
 
@@ -775,17 +797,14 @@ describe("signInWithEmailLink", () => {
 
     const result = await signInWithEmailLink(mockUI, email, link);
 
-    // Verify credential was created correctly
     expect(EmailAuthProvider.credentialWithLink).toHaveBeenCalledWith(email, link);
 
-    // Verify our signInWithCredential function was called with behavior
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
     expect(getBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
 
     expect(mockBehavior).toHaveBeenCalledWith(mockUI, credential);
     expect(result.providerId).toBe("emailLink");
 
-    // Auth method sets pending at start, then idle in finally block.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -802,10 +821,8 @@ describe("signInWithEmailLink", () => {
 
     await signInWithEmailLink(mockUI, email, link);
 
-    // Verify credential was created correctly
     expect(EmailAuthProvider.credentialWithLink).toHaveBeenCalledWith(email, link);
 
-    // Verify our signInWithCredential function was called with behavior
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
     expect(getBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
 
@@ -814,7 +831,6 @@ describe("signInWithEmailLink", () => {
     expect(_signInWithCredential).toHaveBeenCalledWith(mockUI.auth, credential);
     expect(_signInWithCredential).toHaveBeenCalledTimes(1);
 
-    // Calls pending pre-_signInWithCredential call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -831,10 +847,8 @@ describe("signInWithEmailLink", () => {
 
     await signInWithEmailLink(mockUI, email, link);
 
-    // Verify credential was created correctly
     expect(EmailAuthProvider.credentialWithLink).toHaveBeenCalledWith(email, link);
 
-    // Verify our signInWithCredential function was called and error was handled
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
     expect(handleFirebaseError).toHaveBeenCalledWith(mockUI, error);
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
@@ -857,13 +871,11 @@ describe("signInWithCredential", () => {
 
     expect(hasBehavior).toHaveBeenCalledWith(mockUI, "autoUpgradeAnonymousCredential");
 
-    // Calls pending pre-_signInWithCredential call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
 
     expect(_signInWithCredential).toHaveBeenCalledWith(mockUI.auth, credential);
     expect(_signInWithCredential).toHaveBeenCalledTimes(1);
 
-    // Assert that the result is a valid UserCredential.
     expect(result.providerId).toBe("password");
   });
 
@@ -883,7 +895,6 @@ describe("signInWithCredential", () => {
     expect(mockBehavior).toHaveBeenCalledWith(mockUI, credential);
     expect(result.providerId).toBe("password");
 
-    // Auth method sets pending at start, then idle in finally block.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -905,7 +916,6 @@ describe("signInWithCredential", () => {
     expect(_signInWithCredential).toHaveBeenCalledWith(mockUI.auth, credential);
     expect(_signInWithCredential).toHaveBeenCalledTimes(1);
 
-    // Calls pending pre-_signInWithCredential call, then idle after.
     expect(vi.mocked(mockUI.setState).mock.calls).toEqual([["pending"], ["idle"]]);
   });
 
@@ -1034,7 +1044,6 @@ describe("signInWithCustomToken", () => {
 
     await signInWithCustomToken(mockUI, customToken);
 
-    // Verify redirect error is cleared even when network error occurs
     expect(mockUI.setRedirectError).toHaveBeenCalledWith(undefined);
     expect(handleFirebaseError).toHaveBeenCalledWith(mockUI, error);
 
@@ -1050,7 +1059,6 @@ describe("signInWithCustomToken", () => {
 
     await signInWithCustomToken(mockUI, customToken);
 
-    // Verify redirect error is cleared even when token is expired
     expect(mockUI.setRedirectError).toHaveBeenCalledWith(undefined);
     expect(handleFirebaseError).toHaveBeenCalledWith(mockUI, error);
 
@@ -1068,7 +1076,6 @@ describe("signInWithProvider", () => {
     const provider = { providerId: "google.com" } as AuthProvider;
     const mockResult = { user: { uid: "test-user" } } as UserCredential;
 
-    // Mock behaviors - no autoUpgradeAnonymousProvider
     vi.mocked(hasBehavior).mockReturnValue(false);
 
     const mockProviderStrategy = vi.fn().mockResolvedValue(mockResult);
@@ -1104,7 +1111,6 @@ describe("signInWithProvider", () => {
     const provider = { providerId: "google.com" } as AuthProvider;
     const mockResult = { user: { uid: "test-user" } } as UserCredential;
 
-    // Mock behaviors - autoUpgradeAnonymousProvider enabled but returns undefined
     vi.mocked(hasBehavior).mockReturnValue(true);
 
     const mockUpgradeBehavior = vi.fn().mockResolvedValue(undefined);
diff --git a/packages/core/src/auth.ts b/packages/core/src/auth.ts
index 3724a7cc..fe82670e 100644
--- a/packages/core/src/auth.ts
+++ b/packages/core/src/auth.ts
@@ -343,7 +343,7 @@ export function generateTotpQrCode(ui: FirebaseUI, secret: TotpSecret, accountNa
 export async function signInWithMultiFactorAssertion(ui: FirebaseUI, assertion: MultiFactorAssertion) {
   try {
     setPendingState(ui);
-    const result = await ui.multiFactorResolver?.resolveSignIn(assertion);
+    const result = await ui.multiFactorResolver!.resolveSignIn(assertion);
     ui.setMultiFactorResolver(undefined);
     return result;
   } catch (error) {
diff --git a/packages/core/src/schemas.test.ts b/packages/core/src/schemas.test.ts
index ecda98f1..4f21021a 100644
--- a/packages/core/src/schemas.test.ts
+++ b/packages/core/src/schemas.test.ts
@@ -3,6 +3,7 @@ import { createMockUI } from "~/tests/utils";
 import {
   createEmailLinkAuthFormSchema,
   createForgotPasswordAuthFormSchema,
+  createMultiFactorPhoneAuthAssertionNumberFormSchema,
   createPhoneAuthNumberFormSchema,
   createPhoneAuthVerifyFormSchema,
   createSignInAuthFormSchema,
@@ -309,3 +310,77 @@ describe("createPhoneAuthVerifyFormSchema", () => {
     ).toBe(true);
   });
 });
+
+describe("createMultiFactorPhoneAuthAssertionNumberFormSchema", () => {
+  it("should create a multi-factor phone auth assertion number form schema and show missing phone number error", () => {
+    const testLocale = registerLocale("test", {
+      errors: {
+        missingPhoneNumber: "createMultiFactorPhoneAuthAssertionNumberFormSchema + missingPhoneNumber",
+      },
+    });
+
+    const mockUI = createMockUI({
+      locale: testLocale,
+    });
+
+    const schema = createMultiFactorPhoneAuthAssertionNumberFormSchema(mockUI);
+
+    const result = schema.safeParse({
+      phoneNumber: "",
+    });
+
+    expect(result.success).toBe(false);
+    expect(result.error).toBeDefined();
+    expect(result.error?.issues[0]?.message).toBe(
+      "createMultiFactorPhoneAuthAssertionNumberFormSchema + missingPhoneNumber"
+    );
+  });
+
+  it("should create a multi-factor phone auth assertion number form schema and show an error if the phone number is too long", () => {
+    const testLocale = registerLocale("test", {
+      errors: {
+        invalidPhoneNumber: "createMultiFactorPhoneAuthAssertionNumberFormSchema + invalidPhoneNumber",
+      },
+    });
+
+    const mockUI = createMockUI({
+      locale: testLocale,
+    });
+
+    const schema = createMultiFactorPhoneAuthAssertionNumberFormSchema(mockUI);
+
+    const result = schema.safeParse({
+      phoneNumber: "12345678901",
+    });
+
+    expect(result.success).toBe(false);
+    expect(result.error).toBeDefined();
+    expect(result.error?.issues[0]?.message).toBe(
+      "createMultiFactorPhoneAuthAssertionNumberFormSchema + invalidPhoneNumber"
+    );
+  });
+
+  it("should accept valid phone number without requiring displayName", () => {
+    const testLocale = registerLocale("test", {
+      errors: {
+        missingPhoneNumber: "missing",
+        invalidPhoneNumber: "invalid",
+      },
+    });
+
+    const mockUI = createMockUI({
+      locale: testLocale,
+    });
+
+    const schema = createMultiFactorPhoneAuthAssertionNumberFormSchema(mockUI);
+
+    const result = schema.safeParse({
+      phoneNumber: "1234567890",
+    });
+
+    expect(result.success).toBe(true);
+    if (result.success) {
+      expect(result.data).toEqual({ phoneNumber: "1234567890" });
+    }
+  });
+});
diff --git a/packages/core/src/schemas.ts b/packages/core/src/schemas.ts
index 354a0be2..7edf3e64 100644
--- a/packages/core/src/schemas.ts
+++ b/packages/core/src/schemas.ts
@@ -80,6 +80,10 @@ export function createMultiFactorPhoneAuthNumberFormSchema(ui: FirebaseUI) {
   });
 }
 
+export function createMultiFactorPhoneAuthAssertionNumberFormSchema(ui: FirebaseUI) {
+  return createPhoneAuthNumberFormSchema(ui);
+}
+
 export function createMultiFactorPhoneAuthVerifyFormSchema(ui: FirebaseUI) {
   return createPhoneAuthVerifyFormSchema(ui);
 }
diff --git a/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.test.tsx b/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.test.tsx
index e9d60664..394c08a7 100644
--- a/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.test.tsx
+++ b/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.test.tsx
@@ -15,7 +15,7 @@
  */
 
 import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
-import { render, screen, renderHook, cleanup } from "@testing-library/react";
+import { render, screen, renderHook, cleanup, fireEvent, waitFor } from "@testing-library/react";
 import {
   SmsMultiFactorAssertionForm,
   useSmsMultiFactorAssertionPhoneFormAction,
@@ -284,4 +284,65 @@ describe("<SmsMultiFactorAssertionForm />", () => {
       );
     }).not.toThrow();
   });
+
+  it("invokes onSuccess with credential after full SMS verification flow", async () => {
+    const mockUI = createMockUI({
+      locale: registerLocale("test", {
+        labels: {
+          sendCode: "sendCode",
+          phoneNumber: "phoneNumber",
+          verificationCode: "verificationCode",
+          verifyCode: "verifyCode",
+        },
+      }),
+    });
+
+    const mockHint = {
+      factorId: "phone" as const,
+      phoneNumber: "+123456789", // Max 10 chars for schema validation
+      uid: "test-uid",
+      enrollmentTime: "2023-01-01T00:00:00Z",
+    };
+
+    // First step returns a verificationId
+    vi.mocked(verifyPhoneNumber).mockResolvedValue("vid-123");
+    // Second step returns a credential from MFA assertion
+    const mockCredential = { user: { uid: "sms-cred-user" } } as any;
+    vi.mocked(signInWithMultiFactorAssertion).mockResolvedValue(mockCredential);
+
+    const onSuccessMock = vi.fn();
+
+    const { container } = render(
+      createFirebaseUIProvider({
+        children: <SmsMultiFactorAssertionForm hint={mockHint} onSuccess={onSuccessMock} />,
+        ui: mockUI,
+      })
+    );
+
+    const sendCodeForm = screen.getByRole("button", { name: "sendCode" }).closest("form");
+    await act(async () => {
+      fireEvent.submit(sendCodeForm!);
+    });
+
+    const codeInput = await waitFor(() => screen.findByRole("textbox", { name: /verificationCode/i }));
+    const form = codeInput.closest("form");
+
+    await act(async () => {
+      fireEvent.change(codeInput, { target: { value: "123456" } });
+    });
+
+    await act(async () => {
+      fireEvent.submit(form!);
+    });
+
+    await waitFor(() => {
+      expect(verifyPhoneNumber).toHaveBeenCalled();
+      expect(signInWithMultiFactorAssertion).toHaveBeenCalled();
+    });
+
+    expect(onSuccessMock).toHaveBeenCalledTimes(1);
+    expect(onSuccessMock).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "sms-cred-user" }) })
+    );
+  });
 });
diff --git a/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.tsx b/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.tsx
index 21132eac..a29bdc9c 100644
--- a/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.tsx
+++ b/packages/react/src/auth/forms/mfa/sms-multi-factor-assertion-form.tsx
@@ -2,6 +2,7 @@ import { useCallback, useRef, useState } from "react";
 import {
   PhoneAuthProvider,
   PhoneMultiFactorGenerator,
+  type UserCredential,
   type MultiFactorInfo,
   type RecaptchaVerifier,
 } from "firebase/auth";
@@ -9,7 +10,7 @@ import {
 import { signInWithMultiFactorAssertion, FirebaseUIError, getTranslation, verifyPhoneNumber } from "@firebase-ui/core";
 import { form } from "~/components/form";
 import {
-  useMultiFactorPhoneAuthNumberFormSchema,
+  useMultiFactorPhoneAuthAssertionNumberFormSchema,
   useMultiFactorPhoneAuthVerifyFormSchema,
   useRecaptchaVerifier,
   useUI,
@@ -42,7 +43,7 @@ export function useSmsMultiFactorAssertionPhoneForm({
   onSuccess,
 }: UseSmsMultiFactorAssertionPhoneForm) {
   const action = useSmsMultiFactorAssertionPhoneFormAction();
-  const schema = useMultiFactorPhoneAuthNumberFormSchema();
+  const schema = useMultiFactorPhoneAuthAssertionNumberFormSchema();
 
   return form.useAppForm({
     defaultValues: {
@@ -127,7 +128,7 @@ export function useSmsMultiFactorAssertionVerifyFormAction() {
 
 type UseSmsMultiFactorAssertionVerifyForm = {
   verificationId: string;
-  onSuccess: () => void;
+  onSuccess: (credential: UserCredential) => void;
 };
 
 export function useSmsMultiFactorAssertionVerifyForm({
@@ -147,8 +148,8 @@ export function useSmsMultiFactorAssertionVerifyForm({
       onBlur: schema,
       onSubmitAsync: async ({ value }) => {
         try {
-          await action(value);
-          return onSuccess();
+          const credential = await action(value);
+          return onSuccess(credential);
         } catch (error) {
           return error instanceof FirebaseUIError ? error.message : String(error);
         }
@@ -159,7 +160,7 @@ export function useSmsMultiFactorAssertionVerifyForm({
 
 type SmsMultiFactorAssertionVerifyFormProps = {
   verificationId: string;
-  onSuccess: () => void;
+  onSuccess: (credential: UserCredential) => void;
 };
 
 function SmsMultiFactorAssertionVerifyForm(props: SmsMultiFactorAssertionVerifyFormProps) {
@@ -195,7 +196,7 @@ function SmsMultiFactorAssertionVerifyForm(props: SmsMultiFactorAssertionVerifyF
 
 export type SmsMultiFactorAssertionFormProps = {
   hint: MultiFactorInfo;
-  onSuccess?: () => void;
+  onSuccess?: (credential: UserCredential) => void;
 };
 
 export function SmsMultiFactorAssertionForm(props: SmsMultiFactorAssertionFormProps) {
@@ -215,8 +216,8 @@ export function SmsMultiFactorAssertionForm(props: SmsMultiFactorAssertionFormPr
   return (
     <SmsMultiFactorAssertionVerifyForm
       verificationId={verification.verificationId}
-      onSuccess={() => {
-        props.onSuccess?.();
+      onSuccess={(credential) => {
+        props.onSuccess?.(credential);
       }}
     />
   );
diff --git a/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.test.tsx b/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.test.tsx
index 4a20ee06..f4b68674 100644
--- a/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.test.tsx
+++ b/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.test.tsx
@@ -16,7 +16,7 @@
  */
 
 import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
-import { render, screen, renderHook, cleanup } from "@testing-library/react";
+import { render, screen, renderHook, cleanup, fireEvent, waitFor } from "@testing-library/react";
 import {
   TotpMultiFactorAssertionForm,
   useTotpMultiFactorAssertionFormAction,
@@ -204,4 +204,53 @@ describe("<TotpMultiFactorAssertionForm />", () => {
     const input = screen.getByRole("textbox", { name: /verificationCode/i });
     expect(input).toBeInTheDocument();
   });
+
+  it("invokes onSuccess with credential after successful verification", async () => {
+    const mockUI = createMockUI({
+      locale: registerLocale("test", {
+        labels: {
+          verificationCode: "verificationCode",
+          verifyCode: "verifyCode",
+        },
+      }),
+    });
+
+    const mockHint = {
+      factorId: "totp" as const,
+      uid: "test-uid",
+      enrollmentTime: "2023-01-01T00:00:00Z",
+    };
+
+    const mockCredential = { user: { uid: "totp-cred-user" } } as any;
+    vi.mocked(signInWithMultiFactorAssertion).mockResolvedValue(mockCredential);
+
+    const onSuccessMock = vi.fn();
+
+    const { container } = render(
+      createFirebaseUIProvider({
+        children: <TotpMultiFactorAssertionForm hint={mockHint} onSuccess={onSuccessMock} />,
+        ui: mockUI,
+      })
+    );
+
+    const input = screen.getByRole("textbox", { name: /verificationCode/i });
+    const form = input.closest("form");
+
+    await act(async () => {
+      fireEvent.change(input, { target: { value: "123456" } });
+    });
+
+    await act(async () => {
+      fireEvent.submit(form!);
+    });
+
+    await waitFor(() => {
+      expect(signInWithMultiFactorAssertion).toHaveBeenCalled();
+    });
+
+    expect(onSuccessMock).toHaveBeenCalledTimes(1);
+    expect(onSuccessMock).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "totp-cred-user" }) })
+    );
+  });
 });
diff --git a/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.tsx b/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.tsx
index 152385aa..4a4e902c 100644
--- a/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.tsx
+++ b/packages/react/src/auth/forms/mfa/totp-multi-factor-assertion-form.tsx
@@ -1,5 +1,5 @@
 import { useCallback } from "react";
-import { TotpMultiFactorGenerator, type MultiFactorInfo } from "firebase/auth";
+import { TotpMultiFactorGenerator, type UserCredential, type MultiFactorInfo } from "firebase/auth";
 import { signInWithMultiFactorAssertion, FirebaseUIError, getTranslation } from "@firebase-ui/core";
 import { form } from "~/components/form";
 import { useMultiFactorTotpAuthVerifyFormSchema, useUI } from "~/hooks";
@@ -18,7 +18,7 @@ export function useTotpMultiFactorAssertionFormAction() {
 
 type UseTotpMultiFactorAssertionForm = {
   hint: MultiFactorInfo;
-  onSuccess: () => void;
+  onSuccess: (credential: UserCredential) => void;
 };
 
 export function useTotpMultiFactorAssertionForm({ hint, onSuccess }: UseTotpMultiFactorAssertionForm) {
@@ -34,8 +34,8 @@ export function useTotpMultiFactorAssertionForm({ hint, onSuccess }: UseTotpMult
       onBlur: schema,
       onSubmitAsync: async ({ value }) => {
         try {
-          await action({ verificationCode: value.verificationCode, hint });
-          return onSuccess();
+          const credential = await action({ verificationCode: value.verificationCode, hint });
+          return onSuccess(credential);
         } catch (error) {
           return error instanceof FirebaseUIError ? error.message : String(error);
         }
@@ -46,15 +46,15 @@ export function useTotpMultiFactorAssertionForm({ hint, onSuccess }: UseTotpMult
 
 type TotpMultiFactorAssertionFormProps = {
   hint: MultiFactorInfo;
-  onSuccess?: () => void;
+  onSuccess?: (credential: UserCredential) => void;
 };
 
 export function TotpMultiFactorAssertionForm(props: TotpMultiFactorAssertionFormProps) {
   const ui = useUI();
   const form = useTotpMultiFactorAssertionForm({
     hint: props.hint,
-    onSuccess: () => {
-      props.onSuccess?.();
+    onSuccess: (credential) => {
+      props.onSuccess?.(credential);
     },
   });
 
diff --git a/packages/react/src/auth/forms/multi-factor-auth-assertion-form.test.tsx b/packages/react/src/auth/forms/multi-factor-auth-assertion-form.test.tsx
index 5c567759..eb14440c 100644
--- a/packages/react/src/auth/forms/multi-factor-auth-assertion-form.test.tsx
+++ b/packages/react/src/auth/forms/multi-factor-auth-assertion-form.test.tsx
@@ -21,11 +21,25 @@ import { registerLocale } from "@firebase-ui/translations";
 import { FactorId, MultiFactorResolver, PhoneMultiFactorGenerator, TotpMultiFactorGenerator } from "firebase/auth";
 
 vi.mock("~/auth/forms/mfa/sms-multi-factor-assertion-form", () => ({
-  SmsMultiFactorAssertionForm: () => <div data-testid="sms-assertion-form">SMS Assertion Form</div>,
+  SmsMultiFactorAssertionForm: ({ onSuccess }: { onSuccess?: (credential: any) => void }) => (
+    <div>
+      <div data-testid="sms-assertion-form">SMS Assertion Form</div>
+      <button data-testid="sms-on-success" onClick={() => onSuccess?.({ user: { uid: "sms-user" } })}>
+        Trigger SMS Success
+      </button>
+    </div>
+  ),
 }));
 
 vi.mock("~/auth/forms/mfa/totp-multi-factor-assertion-form", () => ({
-  TotpMultiFactorAssertionForm: () => <div data-testid="totp-assertion-form">TOTP Assertion Form</div>,
+  TotpMultiFactorAssertionForm: ({ onSuccess }: { onSuccess?: (credential: any) => void }) => (
+    <div>
+      <div data-testid="totp-assertion-form">TOTP Assertion Form</div>
+      <button data-testid="totp-on-success" onClick={() => onSuccess?.({ user: { uid: "totp-user" } })}>
+        Trigger TOTP Success
+      </button>
+    </div>
+  ),
 }));
 
 vi.mock("~/components/button", () => ({
@@ -79,6 +93,66 @@ describe("<MultiFactorAuthAssertionForm />", () => {
     expect(screen.queryByTestId("mfa-button")).toBeNull();
   });
 
+  it("invokes onSuccess with credential from SMS assertion child", () => {
+    const mockResolver = {
+      auth: {} as any,
+      session: null,
+      hints: [
+        {
+          factorId: PhoneMultiFactorGenerator.FACTOR_ID,
+          uid: "test-uid",
+          displayName: "Test Phone",
+        },
+      ],
+    };
+    const ui = createMockUI();
+    ui.get().setMultiFactorResolver(mockResolver as unknown as MultiFactorResolver);
+
+    const onSuccess = vi.fn();
+
+    render(
+      <CreateFirebaseUIProvider ui={ui}>
+        <MultiFactorAuthAssertionForm onSuccess={onSuccess} />
+      </CreateFirebaseUIProvider>
+    );
+
+    fireEvent.click(screen.getByTestId("sms-on-success"));
+    expect(onSuccess).toHaveBeenCalledTimes(1);
+    expect(onSuccess).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "sms-user" }) })
+    );
+  });
+
+  it("invokes onSuccess with credential from TOTP assertion child", () => {
+    const mockResolver = {
+      auth: {} as any,
+      session: null,
+      hints: [
+        {
+          factorId: TotpMultiFactorGenerator.FACTOR_ID,
+          uid: "test-uid",
+          displayName: "Test TOTP",
+        },
+      ],
+    };
+    const ui = createMockUI();
+    ui.get().setMultiFactorResolver(mockResolver as unknown as MultiFactorResolver);
+
+    const onSuccess = vi.fn();
+
+    render(
+      <CreateFirebaseUIProvider ui={ui}>
+        <MultiFactorAuthAssertionForm onSuccess={onSuccess} />
+      </CreateFirebaseUIProvider>
+    );
+
+    fireEvent.click(screen.getByTestId("totp-on-success"));
+    expect(onSuccess).toHaveBeenCalledTimes(1);
+    expect(onSuccess).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "totp-user" }) })
+    );
+  });
+
   it("auto-selects TOTP factor when only one TOTP hint exists", () => {
     const mockResolver = {
       auth: {} as any,
diff --git a/packages/react/src/auth/forms/multi-factor-auth-assertion-form.tsx b/packages/react/src/auth/forms/multi-factor-auth-assertion-form.tsx
index e60f1c45..36ab2c85 100644
--- a/packages/react/src/auth/forms/multi-factor-auth-assertion-form.tsx
+++ b/packages/react/src/auth/forms/multi-factor-auth-assertion-form.tsx
@@ -1,4 +1,9 @@
-import { PhoneMultiFactorGenerator, TotpMultiFactorGenerator, type MultiFactorInfo } from "firebase/auth";
+import {
+  PhoneMultiFactorGenerator,
+  TotpMultiFactorGenerator,
+  type UserCredential,
+  type MultiFactorInfo,
+} from "firebase/auth";
 import { type ComponentProps, useState } from "react";
 import { useUI } from "~/hooks";
 import { TotpMultiFactorAssertionForm } from "../forms/mfa/totp-multi-factor-assertion-form";
@@ -6,7 +11,11 @@ import { SmsMultiFactorAssertionForm } from "../forms/mfa/sms-multi-factor-asser
 import { Button } from "~/components/button";
 import { getTranslation } from "@firebase-ui/core";
 
-export function MultiFactorAuthAssertionForm() {
+export type MultiFactorAuthAssertionFormProps = {
+  onSuccess?: (credential: UserCredential) => void;
+};
+
+export function MultiFactorAuthAssertionForm(props: MultiFactorAuthAssertionFormProps) {
   const ui = useUI();
   const resolver = ui.multiFactorResolver;
 
@@ -21,11 +30,25 @@ export function MultiFactorAuthAssertionForm() {
 
   if (hint) {
     if (hint.factorId === PhoneMultiFactorGenerator.FACTOR_ID) {
-      return <SmsMultiFactorAssertionForm hint={hint} />;
+      return (
+        <SmsMultiFactorAssertionForm
+          hint={hint}
+          onSuccess={(credential) => {
+            props.onSuccess?.(credential);
+          }}
+        />
+      );
     }
 
     if (hint.factorId === TotpMultiFactorGenerator.FACTOR_ID) {
-      return <TotpMultiFactorAssertionForm hint={hint} />;
+      return (
+        <TotpMultiFactorAssertionForm
+          hint={hint}
+          onSuccess={(credential) => {
+            props.onSuccess?.(credential);
+          }}
+        />
+      );
     }
   }
 
diff --git a/packages/react/src/auth/screens/oauth-screen.test.tsx b/packages/react/src/auth/screens/oauth-screen.test.tsx
index 05e33cd9..92fd79ad 100644
--- a/packages/react/src/auth/screens/oauth-screen.test.tsx
+++ b/packages/react/src/auth/screens/oauth-screen.test.tsx
@@ -14,7 +14,7 @@
  */
 
 import { describe, it, expect, vi, afterEach } from "vitest";
-import { render, screen, cleanup } from "@testing-library/react";
+import { render, screen, cleanup, fireEvent } from "@testing-library/react";
 import { OAuthScreen } from "~/auth/screens/oauth-screen";
 import { CreateFirebaseUIProvider, createMockUI } from "~/tests/utils";
 import { registerLocale } from "@firebase-ui/translations";
@@ -33,7 +33,14 @@ vi.mock("~/components/redirect-error", () => ({
 }));
 
 vi.mock("~/auth/forms/multi-factor-auth-assertion-form", () => ({
-  MultiFactorAuthAssertionForm: () => <div data-testid="mfa-assertion-form">MFA Assertion Form</div>,
+  MultiFactorAuthAssertionForm: ({ onSuccess }: { onSuccess?: (credential: any) => void }) => (
+    <div>
+      <div data-testid="mfa-assertion-form">MFA Assertion Form</div>
+      <button data-testid="mfa-on-success" onClick={() => onSuccess?.({ user: { uid: "oauth-mfa-user" } })}>
+        Trigger MFA Success
+      </button>
+    </div>
+  ),
 }));
 
 afterEach(() => {
@@ -217,4 +224,29 @@ describe("<OAuthScreen />", () => {
     expect(screen.queryByTestId("redirect-error")).toBeNull();
     expect(screen.getByTestId("mfa-assertion-form")).toBeDefined();
   });
+
+  it("calls onSignIn with credential when MFA flow succeeds", () => {
+    const mockResolver = {
+      auth: {} as any,
+      session: null,
+      hints: [],
+    };
+    const ui = createMockUI();
+    ui.get().setMultiFactorResolver(mockResolver as unknown as MultiFactorResolver);
+
+    const onSignIn = vi.fn();
+
+    render(
+      <CreateFirebaseUIProvider ui={ui}>
+        <OAuthScreen onSignIn={onSignIn}>OAuth Provider</OAuthScreen>
+      </CreateFirebaseUIProvider>
+    );
+
+    fireEvent.click(screen.getByTestId("mfa-on-success"));
+
+    expect(onSignIn).toHaveBeenCalledTimes(1);
+    expect(onSignIn).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "oauth-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/react/src/auth/screens/oauth-screen.tsx b/packages/react/src/auth/screens/oauth-screen.tsx
index ac129f45..70cef7c8 100644
--- a/packages/react/src/auth/screens/oauth-screen.tsx
+++ b/packages/react/src/auth/screens/oauth-screen.tsx
@@ -15,6 +15,7 @@
  */
 
 import { getTranslation } from "@firebase-ui/core";
+import { type UserCredential } from "firebase/auth";
 import { type PropsWithChildren } from "react";
 import { useUI } from "~/hooks";
 import { Card, CardContent, CardHeader, CardSubtitle, CardTitle } from "~/components/card";
@@ -22,9 +23,11 @@ import { Policies } from "~/components/policies";
 import { MultiFactorAuthAssertionForm } from "../forms/multi-factor-auth-assertion-form";
 import { RedirectError } from "~/components/redirect-error";
 
-export type OAuthScreenProps = PropsWithChildren;
+export type OAuthScreenProps = PropsWithChildren<{
+  onSignIn?: (credential: UserCredential) => void;
+}>;
 
-export function OAuthScreen({ children }: OAuthScreenProps) {
+export function OAuthScreen({ children, onSignIn }: OAuthScreenProps) {
   const ui = useUI();
 
   const titleText = getTranslation(ui, "labels", "signIn");
@@ -40,7 +43,11 @@ export function OAuthScreen({ children }: OAuthScreenProps) {
         </CardHeader>
         <CardContent className="fui-screen__children">
           {mfaResolver ? (
-            <MultiFactorAuthAssertionForm />
+            <MultiFactorAuthAssertionForm
+              onSuccess={(credential) => {
+                onSignIn?.(credential);
+              }}
+            />
           ) : (
             <>
               {children}
diff --git a/packages/react/src/auth/screens/phone-auth-screen.test.tsx b/packages/react/src/auth/screens/phone-auth-screen.test.tsx
index 090fa60a..0a74ee33 100644
--- a/packages/react/src/auth/screens/phone-auth-screen.test.tsx
+++ b/packages/react/src/auth/screens/phone-auth-screen.test.tsx
@@ -41,7 +41,14 @@ vi.mock("~/components/redirect-error", () => ({
 }));
 
 vi.mock("~/auth/forms/multi-factor-auth-assertion-form", () => ({
-  MultiFactorAuthAssertionForm: () => <div data-testid="mfa-assertion-form">MFA Assertion Form</div>,
+  MultiFactorAuthAssertionForm: ({ onSuccess }: { onSuccess?: (credential: any) => void }) => (
+    <div>
+      <div data-testid="mfa-assertion-form">MFA Assertion Form</div>
+      <button data-testid="mfa-on-success" onClick={() => onSuccess?.({ user: { uid: "phone-mfa-user" } })}>
+        Trigger MFA Success
+      </button>
+    </div>
+  ),
 }));
 
 afterEach(() => {
@@ -243,4 +250,31 @@ describe("<PhoneAuthScreen />", () => {
     expect(screen.queryByTestId("redirect-error")).toBeNull();
     expect(screen.getByTestId("mfa-assertion-form")).toBeDefined();
   });
+
+  it("calls onSignIn with credential when MFA flow succeeds", () => {
+    const mockResolver = {
+      auth: {} as any,
+      session: null,
+      hints: [],
+    };
+    const ui = createMockUI();
+    ui.get().setMultiFactorResolver(mockResolver as unknown as MultiFactorResolver);
+
+    const onSignIn = vi.fn();
+
+    render(
+      <CreateFirebaseUIProvider ui={ui}>
+        <PhoneAuthScreen onSignIn={onSignIn} />
+      </CreateFirebaseUIProvider>
+    );
+
+    // Simulate nested MFA form success
+    const trigger = screen.getByTestId("mfa-on-success");
+    trigger.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+
+    expect(onSignIn).toHaveBeenCalledTimes(1);
+    expect(onSignIn).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "phone-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/react/src/auth/screens/phone-auth-screen.tsx b/packages/react/src/auth/screens/phone-auth-screen.tsx
index 292b0290..6414d757 100644
--- a/packages/react/src/auth/screens/phone-auth-screen.tsx
+++ b/packages/react/src/auth/screens/phone-auth-screen.tsx
@@ -41,7 +41,11 @@ export function PhoneAuthScreen({ children, ...props }: PhoneAuthScreenProps) {
         </CardHeader>
         <CardContent>
           {mfaResolver ? (
-            <MultiFactorAuthAssertionForm />
+            <MultiFactorAuthAssertionForm
+              onSuccess={(credential) => {
+                props.onSignIn?.(credential);
+              }}
+            />
           ) : (
             <>
               <PhoneAuthForm {...props} />
diff --git a/packages/react/src/auth/screens/sign-in-auth-screen.test.tsx b/packages/react/src/auth/screens/sign-in-auth-screen.test.tsx
index 6ef6a76e..7b70c922 100644
--- a/packages/react/src/auth/screens/sign-in-auth-screen.test.tsx
+++ b/packages/react/src/auth/screens/sign-in-auth-screen.test.tsx
@@ -52,7 +52,14 @@ vi.mock("~/components/redirect-error", () => ({
 }));
 
 vi.mock("~/auth/forms/multi-factor-auth-assertion-form", () => ({
-  MultiFactorAuthAssertionForm: () => <div data-testid="mfa-assertion-form">MFA Assertion Form</div>,
+  MultiFactorAuthAssertionForm: ({ onSuccess }: { onSuccess?: (credential: any) => void }) => (
+    <div>
+      <div data-testid="mfa-assertion-form">MFA Assertion Form</div>
+      <button data-testid="mfa-on-success" onClick={() => onSuccess?.({ user: { uid: "mfa-user" } })}>
+        Trigger MFA Success
+      </button>
+    </div>
+  ),
 }));
 
 describe("<SignInAuthScreen />", () => {
@@ -272,4 +279,30 @@ describe("<SignInAuthScreen />", () => {
     expect(screen.queryByTestId("redirect-error")).toBeNull();
     expect(screen.getByTestId("mfa-assertion-form")).toBeDefined();
   });
+
+  it("calls onSignIn with credential when MFA flow succeeds", () => {
+    const mockResolver = {
+      auth: {} as any,
+      session: null,
+      hints: [],
+    };
+    const ui = createMockUI();
+    ui.get().setMultiFactorResolver(mockResolver as unknown as MultiFactorResolver);
+
+    const onSignIn = vi.fn();
+
+    render(
+      <CreateFirebaseUIProvider ui={ui}>
+        <SignInAuthScreen onSignIn={onSignIn} />
+      </CreateFirebaseUIProvider>
+    );
+
+    // Simulate the MFA child reporting success with a credential
+    fireEvent.click(screen.getByTestId("mfa-on-success"));
+
+    expect(onSignIn).toHaveBeenCalledTimes(1);
+    expect(onSignIn).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/react/src/auth/screens/sign-in-auth-screen.tsx b/packages/react/src/auth/screens/sign-in-auth-screen.tsx
index 31af077a..b53c5949 100644
--- a/packages/react/src/auth/screens/sign-in-auth-screen.tsx
+++ b/packages/react/src/auth/screens/sign-in-auth-screen.tsx
@@ -42,7 +42,11 @@ export function SignInAuthScreen({ children, ...props }: SignInAuthScreenProps)
         </CardHeader>
         <CardContent>
           {mfaResolver ? (
-            <MultiFactorAuthAssertionForm />
+            <MultiFactorAuthAssertionForm
+              onSuccess={(credential) => {
+                props.onSignIn?.(credential);
+              }}
+            />
           ) : (
             <>
               <SignInAuthForm {...props} />
diff --git a/packages/react/src/auth/screens/sign-up-auth-screen.test.tsx b/packages/react/src/auth/screens/sign-up-auth-screen.test.tsx
index 9765a0c2..ac5e01d4 100644
--- a/packages/react/src/auth/screens/sign-up-auth-screen.test.tsx
+++ b/packages/react/src/auth/screens/sign-up-auth-screen.test.tsx
@@ -43,7 +43,14 @@ vi.mock("~/components/redirect-error", () => ({
 }));
 
 vi.mock("~/auth/forms/multi-factor-auth-assertion-form", () => ({
-  MultiFactorAuthAssertionForm: () => <div data-testid="mfa-assertion-form">MFA Assertion Form</div>,
+  MultiFactorAuthAssertionForm: ({ onSuccess }: { onSuccess?: (credential: any) => void }) => (
+    <div>
+      <div data-testid="mfa-assertion-form">MFA Assertion Form</div>
+      <button data-testid="mfa-on-success" onClick={() => onSuccess?.({ user: { uid: "signup-mfa-user" } })}>
+        Trigger MFA Success
+      </button>
+    </div>
+  ),
 }));
 
 describe("<SignUpAuthScreen />", () => {
@@ -246,4 +253,31 @@ describe("<SignUpAuthScreen />", () => {
     expect(screen.queryByTestId("redirect-error")).toBeNull();
     expect(screen.getByTestId("mfa-assertion-form")).toBeDefined();
   });
+
+  it("calls onSignUp with credential when MFA flow succeeds", () => {
+    const mockResolver = {
+      auth: {} as any,
+      session: null,
+      hints: [],
+    };
+    const ui = createMockUI();
+    ui.get().setMultiFactorResolver(mockResolver as unknown as MultiFactorResolver);
+
+    const onSignUp = vi.fn();
+
+    render(
+      <CreateFirebaseUIProvider ui={ui}>
+        <SignUpAuthScreen onSignUp={onSignUp} />
+      </CreateFirebaseUIProvider>
+    );
+
+    // Simulate nested MFA form success
+    const trigger = screen.getByTestId("mfa-on-success");
+    trigger.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+
+    expect(onSignUp).toHaveBeenCalledTimes(1);
+    expect(onSignUp).toHaveBeenCalledWith(
+      expect.objectContaining({ user: expect.objectContaining({ uid: "signup-mfa-user" }) })
+    );
+  });
 });
diff --git a/packages/react/src/auth/screens/sign-up-auth-screen.tsx b/packages/react/src/auth/screens/sign-up-auth-screen.tsx
index 70ad50cd..dd3281b6 100644
--- a/packages/react/src/auth/screens/sign-up-auth-screen.tsx
+++ b/packages/react/src/auth/screens/sign-up-auth-screen.tsx
@@ -42,7 +42,11 @@ export function SignUpAuthScreen({ children, ...props }: SignUpAuthScreenProps)
         </CardHeader>
         <CardContent>
           {mfaResolver ? (
-            <MultiFactorAuthAssertionForm />
+            <MultiFactorAuthAssertionForm
+              onSuccess={(credential) => {
+                props.onSignUp?.(credential);
+              }}
+            />
           ) : (
             <>
               <SignUpAuthForm {...props} />
diff --git a/packages/react/src/hooks.test.tsx b/packages/react/src/hooks.test.tsx
index ca0c17fe..cc1d8906 100644
--- a/packages/react/src/hooks.test.tsx
+++ b/packages/react/src/hooks.test.tsx
@@ -24,6 +24,7 @@ import {
   useSignUpAuthFormSchema,
   useForgotPasswordAuthFormSchema,
   useEmailLinkAuthFormSchema,
+  useMultiFactorPhoneAuthAssertionNumberFormSchema,
   usePhoneAuthNumberFormSchema,
   usePhoneAuthVerifyFormSchema,
   useRecaptchaVerifier,
@@ -712,6 +713,116 @@ describe("usePhoneAuthVerifyFormSchema", () => {
   });
 });
 
+describe("useMultiFactorPhoneAuthAssertionNumberFormSchema", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    cleanup();
+  });
+
+  it("returns schema with default English error messages", () => {
+    const mockUI = createMockUI();
+
+    const { result } = renderHook(() => useMultiFactorPhoneAuthAssertionNumberFormSchema(), {
+      wrapper: ({ children }) => createFirebaseUIProvider({ children, ui: mockUI }),
+    });
+
+    const schema = result.current;
+
+    const phoneResult = schema.safeParse({ phoneNumber: "invalid-phone" });
+    expect(phoneResult.success).toBe(false);
+    if (!phoneResult.success) {
+      expect(phoneResult.error.issues[0]!.message).toBe(enUs.translations.errors!.invalidPhoneNumber);
+    }
+  });
+
+  it("returns schema with custom error messages when locale changes", () => {
+    const customTranslations = {
+      errors: {
+        invalidPhoneNumber: "Por favor ingresa un número de teléfono válido",
+      },
+    };
+
+    const customLocale = registerLocale("es-ES", customTranslations);
+    const mockUI = createMockUI({ locale: customLocale });
+
+    const { result } = renderHook(() => useMultiFactorPhoneAuthAssertionNumberFormSchema(), {
+      wrapper: ({ children }) => createFirebaseUIProvider({ children, ui: mockUI }),
+    });
+
+    const schema = result.current;
+
+    const phoneResult = schema.safeParse({ phoneNumber: "invalid-phone" });
+    expect(phoneResult.success).toBe(false);
+    if (!phoneResult.success) {
+      expect(phoneResult.error.issues[0]!.message).toBe("Por favor ingresa un número de teléfono válido");
+    }
+  });
+
+  it("returns stable reference when UI hasn't changed", () => {
+    const mockUI = createMockUI();
+
+    const { result, rerender } = renderHook(() => useMultiFactorPhoneAuthAssertionNumberFormSchema(), {
+      wrapper: ({ children }) => createFirebaseUIProvider({ children, ui: mockUI }),
+    });
+
+    const initialSchema = result.current;
+
+    rerender();
+
+    expect(result.current).toBe(initialSchema);
+  });
+
+  it("returns new schema when locale changes", () => {
+    const mockUI = createMockUI();
+
+    const { result, rerender } = renderHook(() => useMultiFactorPhoneAuthAssertionNumberFormSchema(), {
+      wrapper: ({ children }) => createFirebaseUIProvider({ children, ui: mockUI }),
+    });
+
+    const initialSchema = result.current;
+
+    const customTranslations = {
+      errors: {
+        invalidPhoneNumber: "Custom phone error",
+      },
+    };
+    const customLocale = registerLocale("fr-FR", customTranslations);
+
+    act(() => {
+      mockUI.get().setLocale(customLocale);
+    });
+
+    rerender();
+
+    expect(result.current).not.toBe(initialSchema);
+
+    const phoneResult = result.current.safeParse({ phoneNumber: "invalid-phone" });
+    expect(phoneResult.success).toBe(false);
+
+    if (!phoneResult.success) {
+      expect(phoneResult.error.issues[0]!.message).toBe("Custom phone error");
+    }
+  });
+
+  it("accepts valid phone number without requiring displayName", () => {
+    const mockUI = createMockUI();
+
+    const { result } = renderHook(() => useMultiFactorPhoneAuthAssertionNumberFormSchema(), {
+      wrapper: ({ children }) => createFirebaseUIProvider({ children, ui: mockUI }),
+    });
+
+    const schema = result.current;
+
+    const phoneResult = schema.safeParse({ phoneNumber: "1234567890" });
+    expect(phoneResult.success).toBe(true);
+    if (phoneResult.success) {
+      expect(phoneResult.data).toEqual({ phoneNumber: "1234567890" });
+      // Should not have displayName field
+      expect(phoneResult.data).not.toHaveProperty("displayName");
+    }
+  });
+});
+
 describe("useRedirectError", () => {
   beforeEach(() => {
     vi.clearAllMocks();
diff --git a/packages/react/src/hooks.ts b/packages/react/src/hooks.ts
index 920685a5..1017c7e2 100644
--- a/packages/react/src/hooks.ts
+++ b/packages/react/src/hooks.ts
@@ -20,6 +20,7 @@ import {
   createEmailLinkAuthFormSchema,
   createForgotPasswordAuthFormSchema,
   createMultiFactorPhoneAuthNumberFormSchema,
+  createMultiFactorPhoneAuthAssertionNumberFormSchema,
   createMultiFactorPhoneAuthVerifyFormSchema,
   createMultiFactorTotpAuthNumberFormSchema,
   createMultiFactorTotpAuthVerifyFormSchema,
@@ -92,6 +93,11 @@ export function useMultiFactorPhoneAuthNumberFormSchema() {
   return useMemo(() => createMultiFactorPhoneAuthNumberFormSchema(ui), [ui]);
 }
 
+export function useMultiFactorPhoneAuthAssertionNumberFormSchema() {
+  const ui = useUI();
+  return useMemo(() => createMultiFactorPhoneAuthAssertionNumberFormSchema(ui), [ui]);
+}
+
 export function useMultiFactorPhoneAuthVerifyFormSchema() {
   const ui = useUI();
   return useMemo(() => createMultiFactorPhoneAuthVerifyFormSchema(ui), [ui]);