diff --git a/packages/shield-controller/CHANGELOG.md b/packages/shield-controller/CHANGELOG.md
index ae929cd73ab..336d326a923 100644
--- a/packages/shield-controller/CHANGELOG.md
+++ b/packages/shield-controller/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Make start and stop idempotent ([#6817](https://github.com/MetaMask/core/pull/6817))
+
 ## [0.3.1]
 
 ### Changed
diff --git a/packages/shield-controller/src/ShieldController.test.ts b/packages/shield-controller/src/ShieldController.test.ts
index ac9e8597a5e..b741aaa5dfc 100644
--- a/packages/shield-controller/src/ShieldController.test.ts
+++ b/packages/shield-controller/src/ShieldController.test.ts
@@ -57,12 +57,24 @@ describe('ShieldController', () => {
     it('should trigger checkCoverage when a new transaction is added', async () => {
       const { baseMessenger, backend } = setup();
       const txMeta = generateMockTxMeta();
-      const coverageResultReceived = new Promise<void>((resolve) => {
-        baseMessenger.subscribe(
-          'ShieldController:coverageResultReceived',
-          (_coverageResult) => resolve(),
-        );
-      });
+      const coverageResultReceived = setupCoverageResultReceived(baseMessenger);
+      baseMessenger.publish(
+        'TransactionController:stateChange',
+        { transactions: [txMeta] } as TransactionControllerState,
+        undefined as never,
+      );
+      expect(await coverageResultReceived).toBeUndefined();
+      expect(backend.checkCoverage).toHaveBeenCalledWith({ txMeta });
+    });
+
+    it('should tolerate calling start and stop multiple times', async () => {
+      const { backend, baseMessenger, controller } = setup();
+      controller.stop();
+      controller.stop();
+      controller.start();
+      controller.start();
+      const txMeta = generateMockTxMeta();
+      const coverageResultReceived = setupCoverageResultReceived(baseMessenger);
       baseMessenger.publish(
         'TransactionController:stateChange',
         { transactions: [txMeta] } as TransactionControllerState,
diff --git a/packages/shield-controller/src/ShieldController.ts b/packages/shield-controller/src/ShieldController.ts
index 2208cd7e90b..470f2982709 100644
--- a/packages/shield-controller/src/ShieldController.ts
+++ b/packages/shield-controller/src/ShieldController.ts
@@ -152,6 +152,8 @@ export class ShieldController extends BaseController<
     previousSignatureRequests: Record<string, SignatureRequest> | undefined,
   ) => void;
 
+  #started: boolean;
+
   constructor(options: ShieldControllerOptions) {
     const {
       messenger,
@@ -177,9 +179,15 @@ export class ShieldController extends BaseController<
       this.#handleTransactionControllerStateChange.bind(this);
     this.#signatureControllerStateChangeHandler =
       this.#handleSignatureControllerStateChange.bind(this);
+    this.#started = false;
   }
 
   start() {
+    if (this.#started) {
+      return;
+    }
+    this.#started = true;
+
     this.messagingSystem.subscribe(
       'TransactionController:stateChange',
       this.#transactionControllerStateChangeHandler,
@@ -194,6 +202,11 @@ export class ShieldController extends BaseController<
   }
 
   stop() {
+    if (!this.#started) {
+      return;
+    }
+    this.#started = false;
+
     this.messagingSystem.unsubscribe(
       'TransactionController:stateChange',
       this.#transactionControllerStateChangeHandler,