diff --git a/packages/expect/src/jest-extend.ts b/packages/expect/src/jest-extend.ts
index 3b7df473d..8da7636db 100644
--- a/packages/expect/src/jest-extend.ts
+++ b/packages/expect/src/jest-extend.ts
@@ -80,16 +80,17 @@ function JestExtendPlugin(
           if (
             result
             && typeof result === 'object'
-            && result instanceof Promise
+            && typeof (result as any).then === 'function'
           ) {
-            return result.then(({ pass, message, actual, expected }) => {
+            const thenable = result as PromiseLike<SyncExpectationResult>
+            return thenable.then(({ pass, message, actual, expected }) => {
               if ((pass && isNot) || (!pass && !isNot)) {
                 throw new JestExtendError(message(), actual, expected)
               }
             })
           }
 
-          const { pass, message, actual, expected } = result
+          const { pass, message, actual, expected } = result as SyncExpectationResult
 
           if ((pass && isNot) || (!pass && !isNot)) {
             throw new JestExtendError(message(), actual, expected)
diff --git a/packages/expect/src/utils.ts b/packages/expect/src/utils.ts
index ab33bd7dc..ba09f89d7 100644
--- a/packages/expect/src/utils.ts
+++ b/packages/expect/src/utils.ts
@@ -1,5 +1,6 @@
 import type { Test } from '@vitest/runner/types'
 import type { Assertion } from './types'
+import { noop } from '@vitest/utils'
 import { processError } from '@vitest/utils/error'
 
 export function createAssertionMessage(
@@ -73,12 +74,19 @@ export function recordAsyncExpect(
   return promise
 }
 
+function handleTestError(test: Test, err: unknown) {
+  test.result ||= { state: 'fail' }
+  test.result.state = 'fail'
+  test.result.errors ||= []
+  test.result.errors.push(processError(err))
+}
+
 export function wrapAssertion(
   utils: Chai.ChaiUtils,
   name: string,
-  fn: (this: Chai.AssertionStatic & Assertion, ...args: any[]) => void,
+  fn: (this: Chai.AssertionStatic & Assertion, ...args: any[]) => void | PromiseLike<void>,
 ) {
-  return function (this: Chai.AssertionStatic & Assertion, ...args: any[]): void {
+  return function (this: Chai.AssertionStatic & Assertion, ...args: any[]): void | PromiseLike<void> {
     // private
     if (name !== 'withTest') {
       utils.flag(this, '_name', name)
@@ -95,13 +103,18 @@ export function wrapAssertion(
     }
 
     try {
-      return fn.apply(this, args)
+      const result = fn.apply(this, args)
+
+      if (result && typeof result === 'object' && typeof result.then === 'function') {
+        return result.then(noop, (err) => {
+          handleTestError(test, err)
+        })
+      }
+
+      return result
     }
     catch (err) {
-      test.result ||= { state: 'fail' }
-      test.result.state = 'fail'
-      test.result.errors ||= []
-      test.result.errors.push(processError(err))
+      handleTestError(test, err)
     }
   }
 }
diff --git a/test/cli/fixtures/expect-soft/expects/soft.test.ts b/test/cli/fixtures/expect-soft/expects/soft.test.ts
index ff20fe61a..6d72e483c 100644
--- a/test/cli/fixtures/expect-soft/expects/soft.test.ts
+++ b/test/cli/fixtures/expect-soft/expects/soft.test.ts
@@ -1,6 +1,7 @@
 import { expect, test } from 'vitest'
 
 interface CustomMatchers<R = unknown> {
+  toBeAsync: (expected: unknown) => Promise<R>;
   toBeDividedBy(divisor: number): R
 }
 
@@ -9,6 +10,12 @@ declare module 'vitest' {
 }
 
 expect.extend({
+  toBeAsync: async function (received, expected) {
+    return {
+      pass: received === expected,
+      message: () => `expected ${received} to be ${expected} (asynchronously)`,
+    };
+  },
   toBeDividedBy(received, divisor) {
     const pass = received % divisor === 0
     if (pass) {
@@ -62,6 +69,12 @@ test('with expect.extend', () => {
   expect(5).toEqual(6)
 })
 
+test('promise with expect.extend', async () => {
+  await expect.soft(1 + 1).toBeAsync(3);
+  await expect.soft(1 + 2).toBeAsync(3);
+  await expect.soft(2 + 2).toBeAsync(3);
+});
+
 test('passed', () => {
   expect.soft(1).toEqual(1)
   expect(10).toEqual(10)
diff --git a/test/cli/test/expect-soft.test.ts b/test/cli/test/expect-soft.test.ts
index b968e78a9..d96ad33e2 100644
--- a/test/cli/test/expect-soft.test.ts
+++ b/test/cli/test/expect-soft.test.ts
@@ -40,6 +40,12 @@ describe('expect.soft', () => {
     expect.soft(stderr).toContain('AssertionError: expected 5 to deeply equal 6')
   })
 
+  test('promise with expect.extend', async () => {
+    const { stderr } = await run()
+    expect.soft(stderr).toContain('Error: expected 2 to be 3')
+    expect.soft(stderr).toContain('Error: expected 4 to be 3')
+  })
+
   test('passed', async () => {
     const { stdout } = await run()
     expect.soft(stdout).toContain('soft.test.ts > passed')