diff --git a/packages/happy-dom/src/nodes/html-element/HTMLElement.ts b/packages/happy-dom/src/nodes/html-element/HTMLElement.ts
index 0ef464a72..b553de173 100644
--- a/packages/happy-dom/src/nodes/html-element/HTMLElement.ts
+++ b/packages/happy-dom/src/nodes/html-element/HTMLElement.ts
@@ -398,6 +398,28 @@ export default class HTMLElement extends Element {
 		}
 	}
 
+	/**
+	 * Returns inert.
+	 *
+	 * @returns Inert.
+	 */
+	public get inert(): boolean {
+		return this.getAttribute('inert') !== null;
+	}
+
+	/**
+	 * Returns inert.
+	 *
+	 * @param inert Inert.
+	 */
+	public set inert(inert: boolean) {
+		if (!inert) {
+			this.removeAttribute('inert');
+		} else {
+			this.setAttribute('inert', '');
+		}
+	}
+
 	/**
 	 * Returns language.
 	 *
diff --git a/packages/happy-dom/test/nodes/html-element/HTMLElement.test.ts b/packages/happy-dom/test/nodes/html-element/HTMLElement.test.ts
index 6e59ccb60..7c2324583 100644
--- a/packages/happy-dom/test/nodes/html-element/HTMLElement.test.ts
+++ b/packages/happy-dom/test/nodes/html-element/HTMLElement.test.ts
@@ -361,6 +361,24 @@ describe('HTMLElement', () => {
 		});
 	});
 
+	describe('get inert()', () => {
+		it('Returns the attribute "inert".', () => {
+			const div = <HTMLElement>document.createElement('div');
+			div.setAttribute('inert', '');
+			expect(div.inert).toBe(true);
+		});
+	});
+
+	describe('set inert()', () => {
+		it('Sets the attribute "inert".', () => {
+			const div = <HTMLElement>document.createElement('div');
+			div.inert = true;
+			expect(div.getAttribute('inert')).toBe('');
+			div.inert = false;
+			expect(div.getAttribute('inert')).toBe(null);
+		});
+	});
+
 	for (const property of ['lang', 'title']) {
 		describe(`get ${property}`, () => {
 			it(`Returns the attribute "${property}".`, () => {