diff --git a/API.md b/API.md
index 4b96b5f9f..093cccca2 100644
--- a/API.md
+++ b/API.md
@@ -123,7 +123,7 @@ Once installed the DOM element assertions are available at `assert.dom(...).*`:
 **Parameters**
 
 *   `target` **([string][114] | [HTMLElement][115])** A CSS selector that can be used to find elements using [`querySelector()`][116], or an \[HTMLElement]\[] (Not all assertions support both target types.) (optional, default `rootElement` or `document`)
-*   `rootElement` **[HTMLElement][115]?** The root element of the DOM in which to search for the `target` (optional, default `document`)
+*   `rootElement` **([HTMLElement][115] | [Document][152] | [ShadowRoot][153] | [null][154])?** The root element of the DOM in which to search for the `target` (optional, defaults `document` when `null` or not provided)
 
 **Examples**
 
@@ -1194,3 +1194,9 @@ assert.dom('section#block').doesNotHaveTagName('div');
 [150]: #hasValue
 
 [151]: https://developer.mozilla.org/en-US/docs/Web/API/Element/tagName
+
+[152]: https://developer.mozilla.org/en-US/docs/Web/API/Document
+
+[153]: https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot
+
+[154]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/null
\ No newline at end of file
diff --git a/packages/qunit-dom/lib/__tests__/root-element.ts b/packages/qunit-dom/lib/__tests__/root-element.ts
new file mode 100644
index 000000000..358abc033
--- /dev/null
+++ b/packages/qunit-dom/lib/__tests__/root-element.ts
@@ -0,0 +1,152 @@
+import { describe, beforeEach, test, expect } from 'vitest';
+
+import TestAssertions from '../helpers/test-assertions';
+
+describe('assert.dom(..., rootElement)', () => {
+  let assert: TestAssertions;
+
+  beforeEach(() => {
+    assert = new TestAssertions();
+  });
+
+  test('passing an Element as rootElement', () => {
+    document.body.innerHTML = `
+      <span class="target">dedcoy<span>
+
+      <h1 class="parent">
+        <span class="target">real target<span>
+      </h1>
+    `;
+
+    const rootElement = document.querySelector('.parent');
+
+    assert.dom('.target', rootElement).exists({ count: 1 });
+    assert.dom('.target', rootElement).hasText('real target');
+
+    expect(assert.results).toEqual([
+      {
+        result: true,
+        actual: 'Element .target exists once',
+        expected: 'Element .target exists once',
+        message: 'Element .target exists once',
+      },
+      {
+        result: true,
+        actual: 'real target',
+        expected: 'real target',
+        message: 'Element .target has text "real target"',
+      },
+    ]);
+  });
+
+  test('not passing anything as rootElement', () => {
+    document.body.innerHTML = `
+      <span class="target">decoy<span>
+
+      <h1 class="parent">
+        <span class="target">real target<span>
+      </h1>
+    `;
+
+    assert.dom('.target').exists({ count: 2 });
+
+    expect(assert.results).toEqual([
+      {
+        result: true,
+        actual: 'Element .target exists twice',
+        expected: 'Element .target exists twice',
+        message: 'Element .target exists twice',
+      },
+    ]);
+  });
+
+  test('passing document as rootElement', () => {
+    document.body.innerHTML = `
+      <span class="target">decoy<span>
+
+      <h1 class="parent">
+        <span class="target">real target<span>
+      </h1>
+    `;
+
+    assert.dom('.target', document).exists({ count: 2 });
+
+    expect(assert.results).toEqual([
+      {
+        result: true,
+        actual: 'Element .target exists twice',
+        expected: 'Element .target exists twice',
+        message: 'Element .target exists twice',
+      },
+    ]);
+  });
+
+  test('passing null as rootElement', () => {
+    document.body.innerHTML = `
+      <span class="target">decoy<span>
+
+      <h1 class="parent">
+        <span class="target">real target<span>
+      </h1>
+    `;
+
+    assert.dom('.target', null).exists({ count: 2 });
+
+    expect(assert.results).toEqual([
+      {
+        result: true,
+        actual: 'Element .target exists twice',
+        expected: 'Element .target exists twice',
+        message: 'Element .target exists twice',
+      },
+    ]);
+  });
+
+  test('passing shadow root as rootElement', () => {
+    document.body.innerHTML = `
+      <div id="container">
+        <span class="target">decoy<span>
+      </div>
+    `;
+
+    const container = document.getElementById('container');
+    const shadowRoot = container.attachShadow({ mode: 'closed' });
+
+    shadowRoot.innerHTML = '<span class="target">real target<span>';
+
+    assert.dom('.target').exists({ count: 1 }, 'Only decoy element is found outside shadow root');
+    assert.dom('.target').hasText('real target', 'decoy element text');
+
+    assert.dom('.target', shadowRoot).exists({ count: 1 }, 'Only target found in shadow root');
+    assert.dom('.target', shadowRoot).hasText('real target', 'Target element text');
+
+    console.log(assert.results);
+
+    expect(assert.results).toEqual([
+      {
+        result: true,
+        actual: 'Element .target exists once',
+        expected: 'Element .target exists once',
+        message: 'Only decoy element is found outside shadow root',
+      },
+      {
+        result: false,
+        actual: 'decoy',
+        expected: 'real target',
+        message: 'decoy element text',
+      },
+      {
+        result: true,
+        actual: 'Element .target exists once',
+        expected: 'Element .target exists once',
+        message: 'Only target found in shadow root',
+      },
+      {
+        result: true,
+        actual: 'real target',
+        expected: 'real target',
+        message: 'Target element text',
+      },
+    ]);
+  });
+});
diff --git a/packages/qunit-dom/lib/assertions.ts b/packages/qunit-dom/lib/assertions.ts
index 8549cb018..9de2cfc24 100644
--- a/packages/qunit-dom/lib/assertions.ts
+++ b/packages/qunit-dom/lib/assertions.ts
@@ -31,7 +31,7 @@ type ActualCSSStyleDeclaration = Partial<Record<CSSStyleDeclarationProperty, unk
 export default class DOMAssertions {
   constructor(
     private target: string | Element | null,
-    private rootElement: Element | Document,
+    private rootElement: RootElement,
     private testContext: Assert
   ) {}
 
diff --git a/packages/qunit-dom/lib/helpers/test-assertions.ts b/packages/qunit-dom/lib/helpers/test-assertions.ts
index 253f5b21d..06214ab35 100644
--- a/packages/qunit-dom/lib/helpers/test-assertions.ts
+++ b/packages/qunit-dom/lib/helpers/test-assertions.ts
@@ -3,7 +3,7 @@ import DOMAssertions, { type AssertionResult } from '../assertions.js';
 export default class TestAssertions {
   public results: AssertionResult[] = [];
 
-  dom(target: string | Element | null, rootElement?: Element) {
+  dom(target: string | Element | null, rootElement?: RootElement) {
     return new DOMAssertions(target, rootElement || document, this as any);
   }
 
diff --git a/packages/qunit-dom/lib/install.ts b/packages/qunit-dom/lib/install.ts
index 1053916a2..af8b877ba 100644
--- a/packages/qunit-dom/lib/install.ts
+++ b/packages/qunit-dom/lib/install.ts
@@ -2,13 +2,18 @@ import DOMAssertions from './assertions.js';
 import { getRootElement } from './root-element.js';
 
 declare global {
+  type RootElement = Element | Document | ShadowRoot | null;
+
   interface Assert {
-    dom(target?: string | Element | null, rootElement?: Element): DOMAssertions;
+    dom(target?: string | Element | null, rootElement?: RootElement): DOMAssertions;
   }
 }
 
 export default function (assert: Assert) {
-  assert.dom = function (target?: string | Element | null, rootElement?: Element): DOMAssertions {
+  assert.dom = function (
+    target?: string | Element | null,
+    rootElement?: RootElement
+  ): DOMAssertions {
     if (!isValidRootElement(rootElement)) {
       throw new Error(`${rootElement} is not a valid root element`);
     }