diff --git a/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js b/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js
index d3768ff1b14f7..d1f1bc72a9ed4 100644
--- a/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js
+++ b/packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js
@@ -36,7 +36,7 @@ describe('StrictEffectsMode', () => {
     );
   }
 
-  it('should not double invoke effects in legacy mode', () => {
+  it('should not double invoke effects in legacy mode', async () => {
     function App({text}) {
       React.useEffect(() => {
         Scheduler.log('useEffect mount');
@@ -51,14 +51,14 @@ describe('StrictEffectsMode', () => {
       return text;
     }
 
-    act(() => {
+    await act(async () => {
       ReactTestRenderer.create(<App text={'mount'} />);
     });
 
     assertLog(['useLayoutEffect mount', 'useEffect mount']);
   });
 
-  it('double invoking for effects works properly', () => {
+  it('double invoking for effects works properly', async () => {
     function App({text}) {
       React.useEffect(() => {
         Scheduler.log('useEffect mount');
@@ -74,7 +74,7 @@ describe('StrictEffectsMode', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -93,7 +93,7 @@ describe('StrictEffectsMode', () => {
       assertLog(['useLayoutEffect mount', 'useEffect mount']);
     }
 
-    act(() => {
+    await act(async () => {
       renderer.update(<App text={'update'} />);
     });
 
@@ -104,14 +104,14 @@ describe('StrictEffectsMode', () => {
       'useEffect mount',
     ]);
 
-    act(() => {
+    await act(async () => {
       renderer.unmount();
     });
 
     assertLog(['useLayoutEffect unmount', 'useEffect unmount']);
   });
 
-  it('multiple effects are double invoked in the right order (all mounted, all unmounted, all remounted)', () => {
+  it('multiple effects are double invoked in the right order (all mounted, all unmounted, all remounted)', async () => {
     function App({text}) {
       React.useEffect(() => {
         Scheduler.log('useEffect One mount');
@@ -127,7 +127,7 @@ describe('StrictEffectsMode', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -146,7 +146,7 @@ describe('StrictEffectsMode', () => {
       assertLog(['useEffect One mount', 'useEffect Two mount']);
     }
 
-    act(() => {
+    await act(async () => {
       renderer.update(<App text={'update'} />);
     });
 
@@ -157,14 +157,14 @@ describe('StrictEffectsMode', () => {
       'useEffect Two mount',
     ]);
 
-    act(() => {
+    await act(async () => {
       renderer.unmount(null);
     });
 
     assertLog(['useEffect One unmount', 'useEffect Two unmount']);
   });
 
-  it('multiple layout effects are double invoked in the right order (all mounted, all unmounted, all remounted)', () => {
+  it('multiple layout effects are double invoked in the right order (all mounted, all unmounted, all remounted)', async () => {
     function App({text}) {
       React.useLayoutEffect(() => {
         Scheduler.log('useLayoutEffect One mount');
@@ -180,7 +180,7 @@ describe('StrictEffectsMode', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -199,7 +199,7 @@ describe('StrictEffectsMode', () => {
       assertLog(['useLayoutEffect One mount', 'useLayoutEffect Two mount']);
     }
 
-    act(() => {
+    await act(async () => {
       renderer.update(<App text={'update'} />);
     });
 
@@ -210,14 +210,14 @@ describe('StrictEffectsMode', () => {
       'useLayoutEffect Two mount',
     ]);
 
-    act(() => {
+    await act(async () => {
       renderer.unmount();
     });
 
     assertLog(['useLayoutEffect One unmount', 'useLayoutEffect Two unmount']);
   });
 
-  it('useEffect and useLayoutEffect is called twice when there is no unmount', () => {
+  it('useEffect and useLayoutEffect is called twice when there is no unmount', async () => {
     function App({text}) {
       React.useEffect(() => {
         Scheduler.log('useEffect mount');
@@ -231,7 +231,7 @@ describe('StrictEffectsMode', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -248,20 +248,20 @@ describe('StrictEffectsMode', () => {
       assertLog(['useLayoutEffect mount', 'useEffect mount']);
     }
 
-    act(() => {
+    await act(async () => {
       renderer.update(<App text={'update'} />);
     });
 
     assertLog(['useLayoutEffect mount', 'useEffect mount']);
 
-    act(() => {
+    await act(async () => {
       renderer.unmount();
     });
 
     assertLog([]);
   });
 
-  it('passes the right context to class component lifecycles', () => {
+  it('passes the right context to class component lifecycles', async () => {
     class App extends React.PureComponent {
       test() {}
 
@@ -285,7 +285,7 @@ describe('StrictEffectsMode', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactTestRenderer.create(<App />, {unstable_isConcurrent: true});
     });
 
@@ -300,7 +300,7 @@ describe('StrictEffectsMode', () => {
     }
   });
 
-  it('double invoking works for class components', () => {
+  it('double invoking works for class components', async () => {
     class App extends React.PureComponent {
       componentDidMount() {
         Scheduler.log('componentDidMount');
@@ -320,7 +320,7 @@ describe('StrictEffectsMode', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -336,20 +336,20 @@ describe('StrictEffectsMode', () => {
       assertLog(['componentDidMount']);
     }
 
-    act(() => {
+    await act(async () => {
       renderer.update(<App text={'update'} />);
     });
 
     assertLog(['componentDidUpdate']);
 
-    act(() => {
+    await act(async () => {
       renderer.unmount();
     });
 
     assertLog(['componentWillUnmount']);
   });
 
-  it('should not double invoke class lifecycles in legacy mode', () => {
+  it('should not double invoke class lifecycles in legacy mode', async () => {
     class App extends React.PureComponent {
       componentDidMount() {
         Scheduler.log('componentDidMount');
@@ -368,14 +368,14 @@ describe('StrictEffectsMode', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactTestRenderer.create(<App text={'mount'} />);
     });
 
     assertLog(['componentDidMount']);
   });
 
-  it('double flushing passive effects only results in one double invoke', () => {
+  it('double flushing passive effects only results in one double invoke', async () => {
     function App({text}) {
       const [state, setState] = React.useState(0);
       React.useEffect(() => {
@@ -395,7 +395,7 @@ describe('StrictEffectsMode', () => {
       return text;
     }
 
-    act(() => {
+    await act(async () => {
       ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -430,7 +430,7 @@ describe('StrictEffectsMode', () => {
     }
   });
 
-  it('newly mounted components after initial mount get double invoked', () => {
+  it('newly mounted components after initial mount get double invoked', async () => {
     let _setShowChild;
     function Child() {
       React.useEffect(() => {
@@ -460,7 +460,7 @@ describe('StrictEffectsMode', () => {
       return showChild && <Child />;
     }
 
-    act(() => {
+    await act(async () => {
       ReactTestRenderer.create(<App />, {unstable_isConcurrent: true});
     });
 
@@ -477,7 +477,7 @@ describe('StrictEffectsMode', () => {
       assertLog(['App useLayoutEffect mount', 'App useEffect mount']);
     }
 
-    act(() => {
+    await act(async () => {
       _setShowChild(true);
     });
 
@@ -506,7 +506,7 @@ describe('StrictEffectsMode', () => {
     }
   });
 
-  it('classes and functions are double invoked together correctly', () => {
+  it('classes and functions are double invoked together correctly', async () => {
     class ClassChild extends React.PureComponent {
       componentDidMount() {
         Scheduler.log('componentDidMount');
@@ -543,7 +543,7 @@ describe('StrictEffectsMode', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<App text={'mount'} />, {
         unstable_isConcurrent: true,
       });
@@ -569,7 +569,7 @@ describe('StrictEffectsMode', () => {
       ]);
     }
 
-    act(() => {
+    await act(async () => {
       renderer.update(<App text={'mount'} />);
     });
 
@@ -580,7 +580,7 @@ describe('StrictEffectsMode', () => {
       'useEffect mount',
     ]);
 
-    act(() => {
+    await act(async () => {
       renderer.unmount();
     });
 
diff --git a/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js b/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js
index 6a428567c4a9e..9a7f736fff91a 100644
--- a/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/StrictEffectsModeDefaults-test.internal.js
@@ -37,7 +37,7 @@ describe('StrictEffectsMode defaults', () => {
     ReactFeatureFlags.createRootStrictEffectsByDefault = __DEV__;
   });
 
-  it('should not double invoke effects in legacy mode', () => {
+  it('should not double invoke effects in legacy mode', async () => {
     function App({text}) {
       React.useEffect(() => {
         Scheduler.log('useEffect mount');
@@ -52,14 +52,14 @@ describe('StrictEffectsMode defaults', () => {
       return text;
     }
 
-    act(() => {
+    await act(async () => {
       ReactNoop.renderLegacySyncRoot(<App text={'mount'} />);
     });
 
     assertLog(['useLayoutEffect mount', 'useEffect mount']);
   });
 
-  it('should not double invoke class lifecycles in legacy mode', () => {
+  it('should not double invoke class lifecycles in legacy mode', async () => {
     class App extends React.PureComponent {
       componentDidMount() {
         Scheduler.log('componentDidMount');
@@ -78,7 +78,7 @@ describe('StrictEffectsMode defaults', () => {
       }
     }
 
-    act(() => {
+    await act(async () => {
       ReactNoop.renderLegacySyncRoot(<App text={'mount'} />);
     });
 
@@ -194,7 +194,7 @@ describe('StrictEffectsMode defaults', () => {
       });
     });
 
-    it('double invoking for effects for modern roots', () => {
+    it('double invoking for effects for modern roots', async () => {
       function App({text}) {
         React.useEffect(() => {
           Scheduler.log('useEffect mount');
@@ -208,7 +208,7 @@ describe('StrictEffectsMode defaults', () => {
 
         return text;
       }
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -221,7 +221,7 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'update'} />);
       });
 
@@ -232,14 +232,14 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(null);
       });
 
       assertLog(['useLayoutEffect unmount', 'useEffect unmount']);
     });
 
-    it('multiple effects are double invoked in the right order (all mounted, all unmounted, all remounted)', () => {
+    it('multiple effects are double invoked in the right order (all mounted, all unmounted, all remounted)', async () => {
       function App({text}) {
         React.useEffect(() => {
           Scheduler.log('useEffect One mount');
@@ -254,7 +254,7 @@ describe('StrictEffectsMode defaults', () => {
         return text;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -267,7 +267,7 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect Two mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'update'} />);
       });
 
@@ -278,14 +278,14 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect Two mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(null);
       });
 
       assertLog(['useEffect One unmount', 'useEffect Two unmount']);
     });
 
-    it('multiple layout effects are double invoked in the right order (all mounted, all unmounted, all remounted)', () => {
+    it('multiple layout effects are double invoked in the right order (all mounted, all unmounted, all remounted)', async () => {
       function App({text}) {
         React.useLayoutEffect(() => {
           Scheduler.log('useLayoutEffect One mount');
@@ -300,7 +300,7 @@ describe('StrictEffectsMode defaults', () => {
         return text;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -313,7 +313,7 @@ describe('StrictEffectsMode defaults', () => {
         'useLayoutEffect Two mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'update'} />);
       });
 
@@ -324,14 +324,14 @@ describe('StrictEffectsMode defaults', () => {
         'useLayoutEffect Two mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(null);
       });
 
       assertLog(['useLayoutEffect One unmount', 'useLayoutEffect Two unmount']);
     });
 
-    it('useEffect and useLayoutEffect is called twice when there is no unmount', () => {
+    it('useEffect and useLayoutEffect is called twice when there is no unmount', async () => {
       function App({text}) {
         React.useEffect(() => {
           Scheduler.log('useEffect mount');
@@ -344,7 +344,7 @@ describe('StrictEffectsMode defaults', () => {
         return text;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -355,13 +355,13 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'update'} />);
       });
 
       assertLog(['useLayoutEffect mount', 'useEffect mount']);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(null);
       });
 
@@ -369,7 +369,7 @@ describe('StrictEffectsMode defaults', () => {
     });
 
     //@gate useModernStrictMode
-    it('disconnects refs during double invoking', () => {
+    it('disconnects refs during double invoking', async () => {
       const onRefMock = jest.fn();
       function App({text}) {
         return (
@@ -382,7 +382,7 @@ describe('StrictEffectsMode defaults', () => {
         );
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -392,7 +392,7 @@ describe('StrictEffectsMode defaults', () => {
       expect(onRefMock.mock.calls[2][0]).not.toBeNull();
     });
 
-    it('passes the right context to class component lifecycles', () => {
+    it('passes the right context to class component lifecycles', async () => {
       class App extends React.PureComponent {
         test() {}
 
@@ -416,7 +416,7 @@ describe('StrictEffectsMode defaults', () => {
         }
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App />);
       });
 
@@ -427,7 +427,7 @@ describe('StrictEffectsMode defaults', () => {
       ]);
     });
 
-    it('double invoking works for class components', () => {
+    it('double invoking works for class components', async () => {
       class App extends React.PureComponent {
         componentDidMount() {
           Scheduler.log('componentDidMount');
@@ -446,7 +446,7 @@ describe('StrictEffectsMode defaults', () => {
         }
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -456,20 +456,20 @@ describe('StrictEffectsMode defaults', () => {
         'componentDidMount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'update'} />);
       });
 
       assertLog(['componentDidUpdate']);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(null);
       });
 
       assertLog(['componentWillUnmount']);
     });
 
-    it('double flushing passive effects only results in one double invoke', () => {
+    it('double flushing passive effects only results in one double invoke', async () => {
       function App({text}) {
         const [state, setState] = React.useState(0);
         React.useEffect(() => {
@@ -489,7 +489,7 @@ describe('StrictEffectsMode defaults', () => {
         return text;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -509,7 +509,7 @@ describe('StrictEffectsMode defaults', () => {
       ]);
     });
 
-    it('newly mounted components after initial mount get double invoked', () => {
+    it('newly mounted components after initial mount get double invoked', async () => {
       let _setShowChild;
       function Child() {
         React.useEffect(() => {
@@ -539,7 +539,7 @@ describe('StrictEffectsMode defaults', () => {
         return showChild && <Child />;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App />);
       });
 
@@ -552,7 +552,7 @@ describe('StrictEffectsMode defaults', () => {
         'App useEffect mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         _setShowChild(true);
       });
 
@@ -570,7 +570,7 @@ describe('StrictEffectsMode defaults', () => {
       ]);
     });
 
-    it('classes and functions are double invoked together correctly', () => {
+    it('classes and functions are double invoked together correctly', async () => {
       class ClassChild extends React.PureComponent {
         componentDidMount() {
           Scheduler.log('componentDidMount');
@@ -606,7 +606,7 @@ describe('StrictEffectsMode defaults', () => {
         );
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -622,7 +622,7 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<App text={'mount'} />);
       });
 
@@ -633,7 +633,7 @@ describe('StrictEffectsMode defaults', () => {
         'useEffect mount',
       ]);
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(null);
       });
 
diff --git a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
index 771042fccace4..6220877d16d9d 100644
--- a/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
+++ b/packages/react-reconciler/src/__tests__/useEffectEvent-test.js
@@ -604,7 +604,7 @@ describe('useEffectEvent', () => {
     ReactNoop.render(<Counter value={1} />);
     await waitForAll(['Effect value: 1', 'Event value: 1']);
 
-    act(() => ReactNoop.render(<Counter value={2} />));
+    await act(async () => ReactNoop.render(<Counter value={2} />));
     assertLog(['Effect value: 2', 'Event value: 2']);
   });
 
@@ -742,52 +742,58 @@ describe('useEffectEvent', () => {
       return <Text text={`Welcome to the ${roomId} room!`} />;
     }
 
-    act(() => ReactNoop.render(<ChatRoom roomId="general" theme="light" />));
-    assertLog(['Welcome to the general room!']);
+    await act(async () =>
+      ReactNoop.render(<ChatRoom roomId="general" theme="light" />),
+    );
+    await act(async () => jest.runAllTimers());
+    assertLog(['Welcome to the general room!', 'Connected! theme: light']);
     expect(ReactNoop).toMatchRenderedOutput(
       <span prop="Welcome to the general room!" />,
     );
 
-    jest.advanceTimersByTime(100);
-    Scheduler.unstable_advanceTime(100);
-    assertLog(['Connected! theme: light']);
-
     // change roomId only
-    act(() => ReactNoop.render(<ChatRoom roomId="music" theme="light" />));
-    assertLog(['Welcome to the music room!']);
+    await act(async () =>
+      ReactNoop.render(<ChatRoom roomId="music" theme="light" />),
+    );
+    await act(async () => jest.runAllTimers());
+    assertLog([
+      'Welcome to the music room!',
+      // should trigger a reconnect
+      'Connected! theme: light',
+    ]);
+
     expect(ReactNoop).toMatchRenderedOutput(
       <span prop="Welcome to the music room!" />,
     );
-    jest.advanceTimersByTime(100);
-    Scheduler.unstable_advanceTime(100);
-    // should trigger a reconnect
-    assertLog(['Connected! theme: light']);
 
     // change theme only
-    act(() => ReactNoop.render(<ChatRoom roomId="music" theme="dark" />));
+    await act(async () =>
+      ReactNoop.render(<ChatRoom roomId="music" theme="dark" />),
+    );
+    await act(async () => jest.runAllTimers());
+    // should not trigger a reconnect
     assertLog(['Welcome to the music room!']);
     expect(ReactNoop).toMatchRenderedOutput(
       <span prop="Welcome to the music room!" />,
     );
-    jest.advanceTimersByTime(100);
-    Scheduler.unstable_advanceTime(100);
-    // should not trigger a reconnect
-    await waitForAll([]);
 
     // change roomId only
-    act(() => ReactNoop.render(<ChatRoom roomId="travel" theme="dark" />));
-    assertLog(['Welcome to the travel room!']);
+    await act(async () =>
+      ReactNoop.render(<ChatRoom roomId="travel" theme="dark" />),
+    );
+    await act(async () => jest.runAllTimers());
+    assertLog([
+      'Welcome to the travel room!',
+      // should trigger a reconnect
+      'Connected! theme: dark',
+    ]);
     expect(ReactNoop).toMatchRenderedOutput(
       <span prop="Welcome to the travel room!" />,
     );
-    jest.advanceTimersByTime(100);
-    Scheduler.unstable_advanceTime(100);
-    // should trigger a reconnect
-    assertLog(['Connected! theme: dark']);
   });
 
   // @gate enableUseEffectEventHook
-  it('integration: implements the docs logVisit example', () => {
+  it('integration: implements the docs logVisit example', async () => {
     class AddToCartButton extends React.PureComponent {
       addToCart = () => {
         this.props.onClick();
@@ -835,7 +841,7 @@ describe('useEffectEvent', () => {
     }
 
     const button = React.createRef(null);
-    act(() =>
+    await act(async () =>
       ReactNoop.render(
         <AppShell>
           <Page url="/shop/1" />
@@ -846,7 +852,7 @@ describe('useEffectEvent', () => {
     act(button.current.addToCart);
     assertLog(['Add to cart']);
 
-    act(() =>
+    await act(async () =>
       ReactNoop.render(
         <AppShell>
           <Page url="/shop/2" />
diff --git a/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js b/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
index de3085de0e8fe..a5d9391c668fc 100644
--- a/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
@@ -1666,7 +1666,7 @@ describe('useMutableSource', () => {
     }
 
     // Mount ComponentA with data version 1
-    act(() => {
+    await act(async () => {
       ReactNoop.render(
         <React.Profiler id="root" onRender={onRender}>
           <ComponentA />
@@ -1703,7 +1703,7 @@ describe('useMutableSource', () => {
   if (__DEV__) {
     describe('dev warnings', () => {
       // @gate enableUseMutableSource
-      it('should warn if the subscribe function does not return an unsubscribe function', () => {
+      it('should warn if the subscribe function does not return an unsubscribe function', async () => {
         const source = createSource('one');
         const mutableSource = createMutableSource(
           source,
@@ -1712,8 +1712,8 @@ describe('useMutableSource', () => {
 
         const brokenSubscribe = () => {};
 
-        expect(() => {
-          act(() => {
+        await expect(async () => {
+          await act(async () => {
             ReactNoop.render(
               <Component
                 label="only"
diff --git a/packages/react-reconciler/src/__tests__/useMutableSourceHydration-test.js b/packages/react-reconciler/src/__tests__/useMutableSourceHydration-test.js
index 7bf8d44da5d7c..d008bb9c65a80 100644
--- a/packages/react-reconciler/src/__tests__/useMutableSourceHydration-test.js
+++ b/packages/react-reconciler/src/__tests__/useMutableSourceHydration-test.js
@@ -142,7 +142,7 @@ describe('useMutableSourceHydration', () => {
   }
 
   // @gate enableUseMutableSource
-  it('should render and hydrate', () => {
+  it('should render and hydrate', async () => {
     const source = createSource('one');
     const mutableSource = createMutableSource(source, param => param.version);
 
@@ -165,7 +165,7 @@ describe('useMutableSourceHydration', () => {
     assertLog(['only:one']);
     expect(source.listenerCount).toBe(0);
 
-    act(() => {
+    await act(async () => {
       ReactDOMClient.hydrateRoot(container, <TestComponent />, {
         mutableSources: [mutableSource],
       });
@@ -176,7 +176,7 @@ describe('useMutableSourceHydration', () => {
 
   // @gate enableUseMutableSource
   // @gate enableClientRenderFallbackOnTextMismatch
-  it('should detect a tear before hydrating a component', () => {
+  it('should detect a tear before hydrating a component', async () => {
     const source = createSource('one');
     const mutableSource = createMutableSource(source, param => param.version);
 
@@ -199,8 +199,8 @@ describe('useMutableSourceHydration', () => {
     assertLog(['only:one']);
     expect(source.listenerCount).toBe(0);
 
-    expect(() => {
-      act(() => {
+    await expect(async () => {
+      await act(async () => {
         ReactDOMClient.hydrateRoot(container, <TestComponent />, {
           mutableSources: [mutableSource],
           onRecoverableError(error) {
diff --git a/packages/react-reconciler/src/__tests__/useRef-test.internal.js b/packages/react-reconciler/src/__tests__/useRef-test.internal.js
index ab5635b3c2457..805b27e58c3f9 100644
--- a/packages/react-reconciler/src/__tests__/useRef-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/useRef-test.internal.js
@@ -50,7 +50,7 @@ describe('useRef', () => {
     return <span prop={props.text} />;
   }
 
-  it('creates a ref object initialized with the provided value', () => {
+  it('creates a ref object initialized with the provided value', async () => {
     jest.useFakeTimers();
 
     function useDebouncedCallback(callback, ms, inputs) {
@@ -82,7 +82,7 @@ describe('useRef', () => {
       return null;
     }
 
-    act(() => {
+    await act(async () => {
       ReactNoop.render(<App />);
     });
     assertLog([]);
@@ -134,7 +134,7 @@ describe('useRef', () => {
   });
 
   if (__DEV__) {
-    it('should never warn when attaching to children', () => {
+    it('should never warn when attaching to children', async () => {
       class Component extends React.Component {
         render() {
           return null;
@@ -152,16 +152,16 @@ describe('useRef', () => {
         );
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example phase="mount" />);
       });
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example phase="update" />);
       });
     });
 
     // @gate enableUseRefAccessWarning
-    it('should warn about reads during render', () => {
+    it('should warn about reads during render', async () => {
       function Example() {
         const ref = useRef(123);
         let value;
@@ -173,12 +173,12 @@ describe('useRef', () => {
         return value;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
     });
 
-    it('should not warn about lazy init during render', () => {
+    it('should not warn about lazy init during render', async () => {
       function Example() {
         const ref1 = useRef(null);
         const ref2 = useRef(undefined);
@@ -192,17 +192,17 @@ describe('useRef', () => {
         return null;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
 
       // Should not warn after an update either.
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
     });
 
-    it('should not warn about lazy init outside of render', () => {
+    it('should not warn about lazy init outside of render', async () => {
       function Example() {
         // eslint-disable-next-line no-unused-vars
         const [didMount, setDidMount] = useState(false);
@@ -216,13 +216,13 @@ describe('useRef', () => {
         return null;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
     });
 
     // @gate enableUseRefAccessWarning
-    it('should warn about unconditional lazy init during render', () => {
+    it('should warn about unconditional lazy init during render', async () => {
       function Example() {
         const ref1 = useRef(null);
         const ref2 = useRef(undefined);
@@ -251,19 +251,19 @@ describe('useRef', () => {
       }
 
       let shouldExpectWarning = true;
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
 
       // Should not warn again on update.
       shouldExpectWarning = false;
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
     });
 
     // @gate enableUseRefAccessWarning
-    it('should warn about reads to ref after lazy init pattern', () => {
+    it('should warn about reads to ref after lazy init pattern', async () => {
       function Example() {
         const ref1 = useRef(null);
         const ref2 = useRef(undefined);
@@ -291,13 +291,13 @@ describe('useRef', () => {
         return value;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
     });
 
     // @gate enableUseRefAccessWarning
-    it('should warn about writes to ref after lazy init pattern', () => {
+    it('should warn about writes to ref after lazy init pattern', async () => {
       function Example() {
         const ref1 = useRef(null);
         const ref2 = useRef(undefined);
@@ -323,12 +323,12 @@ describe('useRef', () => {
         return null;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
     });
 
-    it('should not warn about reads or writes within effect', () => {
+    it('should not warn about reads or writes within effect', async () => {
       function Example() {
         const ref = useRef(123);
         useLayoutEffect(() => {
@@ -344,21 +344,21 @@ describe('useRef', () => {
         return null;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
 
       ReactNoop.flushPassiveEffects();
     });
 
-    it('should not warn about reads or writes outside of render phase (e.g. event handler)', () => {
+    it('should not warn about reads or writes outside of render phase (e.g. event handler)', async () => {
       let ref;
       function Example() {
         ref = useRef(123);
         return null;
       }
 
-      act(() => {
+      await act(async () => {
         ReactNoop.render(<Example />);
       });
 
diff --git a/packages/react-reconciler/src/__tests__/useSyncExternalStore-test.js b/packages/react-reconciler/src/__tests__/useSyncExternalStore-test.js
index 96f9c2a292aa7..9e371268c404c 100644
--- a/packages/react-reconciler/src/__tests__/useSyncExternalStore-test.js
+++ b/packages/react-reconciler/src/__tests__/useSyncExternalStore-test.js
@@ -195,19 +195,19 @@ describe('useSyncExternalStore', () => {
     }
 
     const root = ReactNoop.createRoot();
-    act(() => {
+    await act(async () => {
       // Start a render that reads from the store and yields value
       root.render(<App />);
     });
     assertLog(['value:initial']);
 
-    await act(() => {
+    await act(async () => {
       store.set('value:changed');
     });
     assertLog(['value:changed']);
 
     // If cached value was updated, we expect a re-render
-    await act(() => {
+    await act(async () => {
       store.set('value:initial');
     });
     assertLog(['value:initial']);
diff --git a/packages/react-refresh/src/__tests__/ReactFresh-test.js b/packages/react-refresh/src/__tests__/ReactFresh-test.js
index 618e46d6fe34d..0c88a9c0ac06a 100644
--- a/packages/react-refresh/src/__tests__/ReactFresh-test.js
+++ b/packages/react-refresh/src/__tests__/ReactFresh-test.js
@@ -17,6 +17,7 @@ let ReactDOMClient;
 let ReactFreshRuntime;
 let Scheduler;
 let act;
+let internalAct;
 let createReactClass;
 let waitFor;
 let assertLog;
@@ -33,7 +34,8 @@ describe('ReactFresh', () => {
       ReactDOM = require('react-dom');
       ReactDOMClient = require('react-dom/client');
       Scheduler = require('scheduler');
-      act = require('jest-react').act;
+      act = require('react-dom/test-utils').act;
+      internalAct = require('jest-react').act;
 
       const InternalTestUtils = require('internal-test-utils');
       waitFor = InternalTestUtils.waitFor;
@@ -2480,7 +2482,7 @@ describe('ReactFresh', () => {
     expect(el.firstChild.textContent).toBe('0');
     expect(el.firstChild.style.color).toBe('red');
 
-    await act(async () => {
+    await internalAct(async () => {
       el.firstChild.dispatchEvent(
         new MouseEvent('click', {
           bubbles: true,
diff --git a/packages/react-refresh/src/__tests__/ReactFreshIntegration-test.js b/packages/react-refresh/src/__tests__/ReactFreshIntegration-test.js
index ad963c056990e..54e596f6232c3 100644
--- a/packages/react-refresh/src/__tests__/ReactFreshIntegration-test.js
+++ b/packages/react-refresh/src/__tests__/ReactFreshIntegration-test.js
@@ -31,7 +31,7 @@ describe('ReactFreshIntegration', () => {
       ReactFreshRuntime = require('react-refresh/runtime');
       ReactFreshRuntime.injectIntoGlobalHook(global);
       ReactDOM = require('react-dom');
-      act = require('jest-react').act;
+      act = require('react-dom/test-utils').act;
       container = document.createElement('div');
       document.body.appendChild(container);
       exportsObj = undefined;
diff --git a/packages/react-server-dom-relay/src/__tests__/ReactFlightDOMRelay-test.internal.js b/packages/react-server-dom-relay/src/__tests__/ReactFlightDOMRelay-test.internal.js
index 74b9bab83a4d9..c42757b481cc2 100644
--- a/packages/react-server-dom-relay/src/__tests__/ReactFlightDOMRelay-test.internal.js
+++ b/packages/react-server-dom-relay/src/__tests__/ReactFlightDOMRelay-test.internal.js
@@ -85,7 +85,7 @@ describe('ReactFlightDOMRelay', () => {
     });
   });
 
-  it('can render a Client Component using a module reference and render there', () => {
+  it('can render a Client Component using a module reference and render there', async () => {
     function UserClient(props) {
       return (
         <span>
@@ -110,7 +110,7 @@ describe('ReactFlightDOMRelay', () => {
 
     const container = document.createElement('div');
     const root = ReactDOMClient.createRoot(container);
-    act(() => {
+    await act(async () => {
       root.render(modelClient.greeting);
     });
 
diff --git a/packages/use-subscription/src/__tests__/useSubscription-test.js b/packages/use-subscription/src/__tests__/useSubscription-test.js
index 89bf30a7fa2b5..aa4aa5cd0b8c7 100644
--- a/packages/use-subscription/src/__tests__/useSubscription-test.js
+++ b/packages/use-subscription/src/__tests__/useSubscription-test.js
@@ -81,7 +81,7 @@ describe('useSubscription', () => {
 
     const observable = createBehaviorSubject();
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(
         <Subscription source={observable} />,
         {unstable_isConcurrent: true},
@@ -90,14 +90,14 @@ describe('useSubscription', () => {
     assertLog(['default']);
 
     // Updates while subscribed should re-render the child component
-    act(() => observable.next(123));
+    await act(async () => observable.next(123));
     assertLog([123]);
-    act(() => observable.next('abc'));
+    await act(async () => observable.next('abc'));
     assertLog(['abc']);
 
     // Unmounting the subscriber should remove listeners
-    act(() => renderer.update(<div />));
-    act(() => observable.next(456));
+    await act(async () => renderer.update(<div />));
+    await act(async () => observable.next(456));
     await waitForAll([]);
   });
 
@@ -133,21 +133,23 @@ describe('useSubscription', () => {
 
     let observable = createReplaySubject('initial');
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(
         <Subscription source={observable} />,
         {unstable_isConcurrent: true},
       );
     });
     assertLog(['initial']);
-    act(() => observable.next('updated'));
+    await act(async () => observable.next('updated'));
     assertLog(['updated']);
 
     await waitForAll([]);
 
     // Unsetting the subscriber prop should reset subscribed values
     observable = createReplaySubject(undefined);
-    act(() => renderer.update(<Subscription source={observable} />));
+    await act(async () =>
+      renderer.update(<Subscription source={observable} />),
+    );
     assertLog(['default']);
   });
 
@@ -182,7 +184,7 @@ describe('useSubscription', () => {
     expect(subscriptions).toHaveLength(0);
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(
         <Subscription source={observableA} />,
         {unstable_isConcurrent: true},
@@ -195,18 +197,20 @@ describe('useSubscription', () => {
     expect(subscriptions[0]).toBe(observableA);
 
     // Unsetting the subscriber prop should reset subscribed values
-    act(() => renderer.update(<Subscription source={observableB} />));
+    await act(async () =>
+      renderer.update(<Subscription source={observableB} />),
+    );
 
     assertLog(['b-0']);
     expect(subscriptions).toHaveLength(2);
     expect(subscriptions[1]).toBe(observableB);
 
     // Updates to the old subscribable should not re-render the child component
-    act(() => observableA.next('a-1'));
+    await act(async () => observableA.next('a-1'));
     await waitForAll([]);
 
     // Updates to the bew subscribable should re-render the child component
-    act(() => observableB.next('b-1'));
+    await act(async () => observableB.next('b-1'));
     assertLog(['b-1']);
 
     expect(subscriptions).toHaveLength(2);
@@ -241,7 +245,7 @@ describe('useSubscription', () => {
     expect(subscriptions).toHaveLength(0);
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(
         <Subscription source={observableA} />,
         {unstable_isConcurrent: true},
@@ -254,17 +258,19 @@ describe('useSubscription', () => {
     expect(subscriptions[0]).toBe(observableA);
 
     // Unsetting the subscriber prop should reset subscribed values
-    act(() => renderer.update(<Subscription source={observableB} />));
+    await act(async () =>
+      renderer.update(<Subscription source={observableB} />),
+    );
     assertLog(['b-0']);
     expect(subscriptions).toHaveLength(2);
     expect(subscriptions[1]).toBe(observableB);
 
     // Updates to the old subscribable should not re-render the child component
-    act(() => observableA.next('a-1'));
+    await act(async () => observableA.next('a-1'));
     await waitForAll([]);
 
     // Updates to the bew subscribable should re-render the child component
-    act(() => observableB.next('b-1'));
+    await act(async () => observableB.next('b-1'));
     assertLog(['b-1']);
 
     expect(subscriptions).toHaveLength(2);
@@ -329,7 +335,7 @@ describe('useSubscription', () => {
     const observableB = createBehaviorSubject('b-0');
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<Parent observed={observableA} />, {
         unstable_isConcurrent: true,
       });
@@ -353,7 +359,7 @@ describe('useSubscription', () => {
     });
 
     // Update again
-    act(() => renderer.update(<Parent observed={observableA} />));
+    await act(async () => renderer.update(<Parent observed={observableA} />));
 
     // Flush everything and ensure that the correct subscribable is used
     // We expect the last emitted update to be rendered (because of the commit phase value check)
@@ -432,7 +438,7 @@ describe('useSubscription', () => {
     const observableB = createBehaviorSubject('b-0');
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(<Parent observed={observableA} />, {
         unstable_isConcurrent: true,
       });
@@ -474,12 +480,12 @@ describe('useSubscription', () => {
 
     // Updates from the new subscribable should be ignored.
     log.splice(0);
-    act(() => observableB.next('b-1'));
+    await act(async () => observableB.next('b-1'));
     await waitForAll([]);
     expect(log).toEqual([]);
   });
 
-  it('should guard against updates that happen after unmounting', () => {
+  it('should guard against updates that happen after unmounting', async () => {
     function Child({value = 'default'}) {
       Scheduler.log(value);
       return null;
@@ -529,7 +535,7 @@ describe('useSubscription', () => {
     });
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(
         <Subscription source={eventHandler} />,
         {unstable_isConcurrent: true},
@@ -563,7 +569,7 @@ describe('useSubscription', () => {
     }
 
     let renderer;
-    act(() => {
+    await act(async () => {
       renderer = ReactTestRenderer.create(
         <Subscription subscription={subscription1} />,
         {unstable_isConcurrent: true},
@@ -571,7 +577,9 @@ describe('useSubscription', () => {
     });
     await waitForAll([]);
 
-    act(() => renderer.update(<Subscription subscription={subscription2} />));
+    await act(async () =>
+      renderer.update(<Subscription subscription={subscription2} />),
+    );
     await waitForAll([]);
   });