diff --git a/packages/react-reconciler/src/ReactFiberScheduler.js b/packages/react-reconciler/src/ReactFiberScheduler.js
index 5ca08cebc0925..38ef8c44d528e 100644
--- a/packages/react-reconciler/src/ReactFiberScheduler.js
+++ b/packages/react-reconciler/src/ReactFiberScheduler.js
@@ -49,7 +49,6 @@ import {
   enableUserTimingAPI,
   replayFailedUnitOfWorkWithInvokeGuardedCallback,
   warnAboutDeprecatedLifecycles,
-  warnAboutLegacyContextAPI,
   enableSuspense,
 } from 'shared/ReactFeatureFlags';
 import getComponentName from 'shared/getComponentName';
@@ -479,14 +478,11 @@ function commitAllLifeCycles(
 ) {
   if (__DEV__) {
     ReactStrictModeWarnings.flushPendingUnsafeLifecycleWarnings();
+    ReactStrictModeWarnings.flushLegacyContextWarning();
 
     if (warnAboutDeprecatedLifecycles) {
       ReactStrictModeWarnings.flushPendingDeprecationWarnings();
     }
-
-    if (warnAboutLegacyContextAPI) {
-      ReactStrictModeWarnings.flushLegacyContextWarning();
-    }
   }
   while (nextEffect !== null) {
     const effectTag = nextEffect.effectTag;
diff --git a/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js
index 5260851a9e324..8a53360c7882f 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncremental-test.internal.js
@@ -1936,7 +1936,11 @@ describe('ReactIncremental', () => {
         </div>
       </Intl>,
     );
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Intl, ShowBoth, ShowLocale',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'Intl {}',
       'ShowLocale {"locale":"fr"}',
@@ -1981,7 +1985,11 @@ describe('ReactIncremental', () => {
         <ShowBoth />
       </Intl>,
     );
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Router, ShowRoute',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'ShowLocale {"locale":"sv"}',
       'ShowBoth {"locale":"sv"}',
@@ -2021,7 +2029,11 @@ describe('ReactIncremental', () => {
     }
 
     ReactNoop.render(<Recurse />);
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Recurse',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'Recurse {}',
       'Recurse {"n":2}',
@@ -2054,7 +2066,11 @@ describe('ReactIncremental', () => {
     };
 
     ReactNoop.render(<Recurse />);
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Recurse',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'Recurse {}',
       'Recurse {"n":2}',
@@ -2112,7 +2128,11 @@ describe('ReactIncremental', () => {
     ]);
 
     ops.length = 0;
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Intl, ShowLocale',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'ShowLocale {"locale":"fr"}',
       'Intl {}',
@@ -2192,7 +2212,11 @@ describe('ReactIncremental', () => {
         </IndirectionFn>
       </Intl>,
     );
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Intl, ShowLocaleClass, ShowLocaleFn',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'Intl:read {}',
       'Intl:provide {"locale":"fr"}',
@@ -2280,7 +2304,11 @@ describe('ReactIncremental', () => {
         </IndirectionFn>
       </Stateful>,
     );
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Intl, ShowLocaleClass, ShowLocaleFn',
+      {withoutStack: true},
+    );
     expect(ops).toEqual([
       'Intl:read {}',
       'Intl:provide {"locale":"fr"}',
@@ -2345,7 +2373,11 @@ describe('ReactIncremental', () => {
 
     // Init
     ReactNoop.render(<Root />);
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Child',
+      {withoutStack: true},
+    );
 
     // Trigger an update in the middle of the tree
     instance.setState({});
@@ -2391,7 +2423,11 @@ describe('ReactIncremental', () => {
 
     // Init
     ReactNoop.render(<Root />);
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: ContextProvider',
+      {withoutStack: true},
+    );
 
     // Trigger an update in the middle of the tree
     // This is necessary to reproduce the error as it curently exists.
@@ -2437,8 +2473,12 @@ describe('ReactIncremental', () => {
 
     ReactNoop.render(<MyComponent />);
     expect(ReactNoop.flush).toWarnDev(
-      'componentWillReceiveProps: Please update the following components ' +
-        'to use static getDerivedStateFromProps instead: MyComponent',
+      [
+        'componentWillReceiveProps: Please update the following components ' +
+          'to use static getDerivedStateFromProps instead: MyComponent',
+        'Legacy context API has been detected within a strict-mode tree: \n\n' +
+          'Please update the following components: MyComponent',
+      ],
       {withoutStack: true},
     );
 
@@ -2582,7 +2622,11 @@ describe('ReactIncremental', () => {
       </TopContextProvider>,
     );
 
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Child, TopContextProvider',
+      {withoutStack: true},
+    );
     expect(rendered).toEqual(['count:0']);
     instance.updateCount();
     ReactNoop.flush();
@@ -2640,7 +2684,11 @@ describe('ReactIncremental', () => {
       </TopContextProvider>,
     );
 
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Child, MiddleContextProvider, TopContextProvider',
+      {withoutStack: true},
+    );
     expect(rendered).toEqual(['count:0']);
     instance.updateCount();
     ReactNoop.flush();
@@ -2707,7 +2755,11 @@ describe('ReactIncremental', () => {
       </TopContextProvider>,
     );
 
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Child, MiddleContextProvider, TopContextProvider',
+      {withoutStack: true},
+    );
     expect(rendered).toEqual(['count:0']);
     instance.updateCount();
     ReactNoop.flush();
@@ -2784,7 +2836,11 @@ describe('ReactIncremental', () => {
       </TopContextProvider>,
     );
 
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Child, MiddleContextProvider, TopContextProvider',
+      {withoutStack: true},
+    );
     expect(rendered).toEqual(['count:0, name:brian']);
     topInstance.updateCount();
     ReactNoop.flush();
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js
index eab804cedb39e..345c5b537f2c5 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js
@@ -1092,7 +1092,11 @@ describe('ReactIncrementalErrorHandling', () => {
         <Connector />
       </Provider>,
     );
-    ReactNoop.flush();
+    expect(ReactNoop.flush).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Connector, Provider',
+      {withoutStack: true},
+    );
 
     // If the context stack does not unwind, span will get 'abcde'
     expect(ReactNoop.getChildren()).toEqual([span('a')]);
@@ -1581,6 +1585,12 @@ describe('ReactIncrementalErrorHandling', () => {
     };
 
     ReactNoop.render(<Provider />);
-    expect(() => ReactNoop.flush()).toThrow('Oops!');
+    expect(() => {
+      expect(() => ReactNoop.flush()).toThrow('Oops!');
+    }).toWarnDev(
+      'Legacy context API has been detected within a strict-mode tree: \n\n' +
+        'Please update the following components: Provider',
+      {withoutStack: true},
+    );
   });
 });
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js
index bc1dca7adf592..801e64b14839c 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalPerf-test.internal.js
@@ -357,12 +357,16 @@ describe('ReactDebugFiberPerf', () => {
     ReactNoop.render(<AllLifecycles />);
     addComment('Mount');
     expect(ReactNoop.flush).toWarnDev(
-      'componentWillMount: Please update the following components ' +
-        'to use componentDidMount instead: AllLifecycles' +
-        '\n\ncomponentWillReceiveProps: Please update the following components ' +
-        'to use static getDerivedStateFromProps instead: AllLifecycles' +
-        '\n\ncomponentWillUpdate: Please update the following components ' +
-        'to use componentDidUpdate instead: AllLifecycles',
+      [
+        'componentWillMount: Please update the following components ' +
+          'to use componentDidMount instead: AllLifecycles' +
+          '\n\ncomponentWillReceiveProps: Please update the following components ' +
+          'to use static getDerivedStateFromProps instead: AllLifecycles' +
+          '\n\ncomponentWillUpdate: Please update the following components ' +
+          'to use componentDidUpdate instead: AllLifecycles',
+        'Legacy context API has been detected within a strict-mode tree: \n\n' +
+          'Please update the following components: AllLifecycles',
+      ],
       {withoutStack: true},
     );
     ReactNoop.render(<AllLifecycles />);
diff --git a/packages/react-reconciler/src/__tests__/ReactNewContext-test.internal.js b/packages/react-reconciler/src/__tests__/ReactNewContext-test.internal.js
index 8a03208219326..299b6ab10811f 100644
--- a/packages/react-reconciler/src/__tests__/ReactNewContext-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactNewContext-test.internal.js
@@ -1144,7 +1144,13 @@ describe('ReactNewContext', () => {
           </App>
         </LegacyProvider>,
       );
-      expect(ReactNoop.flush()).toEqual(['LegacyProvider', 'App', 'Child']);
+      expect(() => {
+        expect(ReactNoop.flush()).toEqual(['LegacyProvider', 'App', 'Child']);
+      }).toWarnDev(
+        'Legacy context API has been detected within a strict-mode tree: \n\n' +
+          'Please update the following components: LegacyProvider',
+        {withoutStack: true},
+      );
       expect(ReactNoop.getChildren()).toEqual([span('Child')]);
 
       // Update App with same value (should bail out)
diff --git a/packages/react/src/__tests__/ReactStrictMode-test.internal.js b/packages/react/src/__tests__/ReactStrictMode-test.internal.js
index 896c7c179e301..fc279a50a2301 100644
--- a/packages/react/src/__tests__/ReactStrictMode-test.internal.js
+++ b/packages/react/src/__tests__/ReactStrictMode-test.internal.js
@@ -822,8 +822,6 @@ describe('ReactStrictMode', () => {
       React = require('react');
       ReactTestRenderer = require('react-test-renderer');
       PropTypes = require('prop-types');
-      ReactFeatureFlags = require('shared/ReactFeatureFlags');
-      ReactFeatureFlags.warnAboutLegacyContextAPI = true;
     });
 
     it('should warn if the legacy context API have been used in strict mode', () => {
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index abd23679539d3..38fafa73a46dd 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -28,9 +28,6 @@ export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 // Warn about deprecated, async-unsafe lifecycles; relates to RFC #6:
 export const warnAboutDeprecatedLifecycles = false;
 
-// Warn about legacy context API
-export const warnAboutLegacyContextAPI = false;
-
 // Gather advanced timing metrics for Profiler subtrees.
 export const enableProfilerTimer = __PROFILE__;
 
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
index 566d271222701..9a03b482d24fb 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
@@ -17,7 +17,6 @@ export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
 export const enableSuspense = false;
 export const warnAboutDeprecatedLifecycles = false;
-export const warnAboutLegacyContextAPI = __DEV__;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
 export const enableSchedulerTracing = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js b/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
index f9b6576d4f464..9a2c8dfc7c235 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
@@ -17,7 +17,6 @@ export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
 export const enableSuspense = false;
 export const warnAboutDeprecatedLifecycles = false;
-export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
 export const enableSchedulerTracing = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 4b12e739183d0..1ea9549a1a81e 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -24,7 +24,6 @@ export const {
 
 // The rest of the flags are static for better dead code elimination.
 export const enableUserTimingAPI = __DEV__;
-export const warnAboutLegacyContextAPI = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
 export const enableSchedulerTracing = __PROFILE__;
 export const enableSuspenseServerRenderer = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index a92e3c0f953f5..780563724d8b9 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -18,7 +18,6 @@ export const enableSuspense = false;
 export const enableUserTimingAPI = __DEV__;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const warnAboutDeprecatedLifecycles = false;
-export const warnAboutLegacyContextAPI = false;
 export const enableProfilerTimer = __PROFILE__;
 export const enableSchedulerTracing = __PROFILE__;
 export const enableSuspenseServerRenderer = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.persistent.js b/packages/shared/forks/ReactFeatureFlags.persistent.js
index 1fb299db333fb..ebe62b122cfd1 100644
--- a/packages/shared/forks/ReactFeatureFlags.persistent.js
+++ b/packages/shared/forks/ReactFeatureFlags.persistent.js
@@ -17,7 +17,6 @@ export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
 export const enableSuspense = false;
 export const warnAboutDeprecatedLifecycles = false;
-export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
 export const enableSchedulerTracing = __PROFILE__;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index 07fde5086acc3..922771420b57e 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -17,7 +17,6 @@ export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
 export const enableSuspense = false;
 export const warnAboutDeprecatedLifecycles = false;
-export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;
 export const enableSchedulerTracing = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index 20e510afa1b9a..dcd4b70ae0fa2 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -17,7 +17,6 @@ export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
 export const enableSuspense = true;
 export const warnAboutDeprecatedLifecycles = false;
-export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;
 export const enableSchedulerTracing = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 414bc4052b2ae..a0c8931a5c21d 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -21,9 +21,6 @@ export const {
   disableInputAttributeSyncing,
 } = require('ReactFeatureFlags');
 
-// The rest of the flags are static for better dead code elimination.
-export const warnAboutLegacyContextAPI = __DEV__;
-
 // In www, we have experimental support for gathering data
 // from User Timing API calls in production. By default, we
 // only emit performance.mark/measure calls in __DEV__. But if
diff --git a/scripts/rollup/shims/react-native-fb/ReactFeatureFlags.js b/scripts/rollup/shims/react-native-fb/ReactFeatureFlags.js
index df11ce7303929..55ef3d80b1964 100644
--- a/scripts/rollup/shims/react-native-fb/ReactFeatureFlags.js
+++ b/scripts/rollup/shims/react-native-fb/ReactFeatureFlags.js
@@ -14,7 +14,6 @@ const ReactFeatureFlags = {
   debugRenderPhaseSideEffects: false,
   debugRenderPhaseSideEffectsForStrictMode: false,
   warnAboutDeprecatedLifecycles: true,
-  warnAboutLegacyContextAPI: true,
 };
 
 module.exports = ReactFeatureFlags;