diff --git a/scripts/rollup/forks.js b/scripts/rollup/forks.js
index 9cab6e5be390..d4a392770bbf 100644
--- a/scripts/rollup/forks.js
+++ b/scripts/rollup/forks.js
@@ -30,10 +30,22 @@ const __EXPERIMENTAL__ =
 
 // If you need to replace a file with another file for a specific environment,
 // add it to this list with the logic for choosing the right replacement.
+
+// Fork paths are relative to the project root. They must include the full path,
+// including the extension. We intentionally don't use Node's module resolution
+// algorithm because 1) require.resolve doesn't work with ESM modules, and 2)
+// the behavior is easier to predict.
 const forks = Object.freeze({
   // Optimization: for UMDs, use a version that we can inline into the React bundle.
   // Use that from all other bundles.
-  'object-assign': (bundleType, entry, dependencies) => {
+
+  // NOTE: This is hard-coded to the main entry point of the (third-party)
+  // object-assign package.
+  './node_modules/object-assign/index.js': (
+    bundleType,
+    entry,
+    dependencies
+  ) => {
     if (
       bundleType !== UMD_DEV &&
       bundleType !== UMD_PROD &&
@@ -45,7 +57,7 @@ const forks = Object.freeze({
     }
     if (entry === 'react' || entry === 'react/unstable-shared-subset') {
       // Use the forked version that uses ES modules instead of CommonJS.
-      return 'shared/forks/object-assign.inline-umd.js';
+      return './packages/shared/forks/object-assign.inline-umd.js';
     }
     if (dependencies.indexOf('react') === -1) {
       // We can only apply the optimizations to bundle that depend on React
@@ -53,19 +65,25 @@ const forks = Object.freeze({
       return null;
     }
     // We can use the fork that reads the secret export!
-    return 'shared/forks/object-assign.umd.js';
+    return './packages/shared/forks/object-assign.umd.js';
   },
 
-  'react-shallow-renderer': () => {
+  // NOTE: This is hard-coded to the main entry point of the (third-party)
+  // react-shallow-renderer package.
+  './node_modules/react-shallow-renderer/index.js': () => {
     // Use ESM build of `react-shallow-renderer`.
-    return 'react-shallow-renderer/esm/index.js';
+    return './node_modules/react-shallow-renderer/esm/index.js';
   },
 
   // Without this fork, importing `shared/ReactSharedInternals` inside
   // the `react` package itself would not work due to a cyclical dependency.
-  'shared/ReactSharedInternals': (bundleType, entry, dependencies) => {
+  './packages/shared/ReactSharedInternals.js': (
+    bundleType,
+    entry,
+    dependencies
+  ) => {
     if (entry === 'react' || entry === 'react/unstable-shared-subset') {
-      return 'react/src/ReactSharedInternals.js';
+      return './packages/react/src/ReactSharedInternals.js';
     }
     if (!entry.startsWith('react/') && dependencies.indexOf('react') === -1) {
       // React internals are unavailable if we can't reference the package.
@@ -82,18 +100,18 @@ const forks = Object.freeze({
   },
 
   // We have a few forks for different environments.
-  'shared/ReactFeatureFlags': (bundleType, entry) => {
+  './packages/shared/ReactFeatureFlags.js': (bundleType, entry) => {
     switch (entry) {
       case 'react-native-renderer':
         switch (bundleType) {
           case RN_FB_DEV:
           case RN_FB_PROD:
           case RN_FB_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.native-fb.js';
+            return './packages/shared/forks/ReactFeatureFlags.native-fb.js';
           case RN_OSS_DEV:
           case RN_OSS_PROD:
           case RN_OSS_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.native-oss.js';
+            return './packages/shared/forks/ReactFeatureFlags.native-oss.js';
           default:
             throw Error(
               `Unexpected entry (${entry}) and bundleType (${bundleType})`
@@ -104,11 +122,11 @@ const forks = Object.freeze({
           case RN_FB_DEV:
           case RN_FB_PROD:
           case RN_FB_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.native-fb.js';
+            return './packages/shared/forks/ReactFeatureFlags.native-fb.js';
           case RN_OSS_DEV:
           case RN_OSS_PROD:
           case RN_OSS_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.native-oss.js';
+            return './packages/shared/forks/ReactFeatureFlags.native-oss.js';
           default:
             throw Error(
               `Unexpected entry (${entry}) and bundleType (${bundleType})`
@@ -122,37 +140,37 @@ const forks = Object.freeze({
           case RN_OSS_DEV:
           case RN_OSS_PROD:
           case RN_OSS_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.test-renderer.native.js';
+            return './packages/shared/forks/ReactFeatureFlags.test-renderer.native.js';
           case FB_WWW_DEV:
           case FB_WWW_PROD:
           case FB_WWW_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.test-renderer.www.js';
+            return './packages/shared/forks/ReactFeatureFlags.test-renderer.www.js';
         }
-        return 'shared/forks/ReactFeatureFlags.test-renderer.js';
+        return './packages/shared/forks/ReactFeatureFlags.test-renderer.js';
       case 'react-dom/unstable_testing':
         switch (bundleType) {
           case FB_WWW_DEV:
           case FB_WWW_PROD:
           case FB_WWW_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.testing.www.js';
+            return './packages/shared/forks/ReactFeatureFlags.testing.www.js';
         }
-        return 'shared/forks/ReactFeatureFlags.testing.js';
+        return './packages/shared/forks/ReactFeatureFlags.testing.js';
       default:
         switch (bundleType) {
           case FB_WWW_DEV:
           case FB_WWW_PROD:
           case FB_WWW_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.www.js';
+            return './packages/shared/forks/ReactFeatureFlags.www.js';
           case RN_FB_DEV:
           case RN_FB_PROD:
           case RN_FB_PROFILING:
-            return 'shared/forks/ReactFeatureFlags.native-fb.js';
+            return './packages/shared/forks/ReactFeatureFlags.native-fb.js';
         }
     }
     return null;
   },
 
-  scheduler: (bundleType, entry, dependencies) => {
+  './packages/scheduler/index.js': (bundleType, entry, dependencies) => {
     switch (bundleType) {
       case UMD_DEV:
       case UMD_PROD:
@@ -164,28 +182,32 @@ const forks = Object.freeze({
         }
         // Optimization: for UMDs, use the API that is already a part of the React
         // package instead of requiring it to be loaded via a separate <script> tag
-        return 'shared/forks/Scheduler.umd.js';
+        return './packages/shared/forks/Scheduler.umd.js';
       default:
         // For other bundles, use the shared NPM package.
         return null;
     }
   },
 
-  'scheduler/src/SchedulerFeatureFlags': (bundleType, entry, dependencies) => {
+  './packages/scheduler/src/SchedulerFeatureFlags.js': (
+    bundleType,
+    entry,
+    dependencies
+  ) => {
     if (
       bundleType === FB_WWW_DEV ||
       bundleType === FB_WWW_PROD ||
       bundleType === FB_WWW_PROFILING
     ) {
-      return 'scheduler/src/forks/SchedulerFeatureFlags.www.js';
+      return './packages/scheduler/src/forks/SchedulerFeatureFlags.www.js';
     }
-    return 'scheduler/src/SchedulerFeatureFlags';
+    return './packages/scheduler/src/SchedulerFeatureFlags.js';
   },
 
-  'shared/consoleWithStackDev': (bundleType, entry) => {
+  './packages/shared/consoleWithStackDev.js': (bundleType, entry) => {
     switch (bundleType) {
       case FB_WWW_DEV:
-        return 'shared/forks/consoleWithStackDev.www.js';
+        return './packages/shared/forks/consoleWithStackDev.www.js';
       default:
         return null;
     }
@@ -193,12 +215,12 @@ const forks = Object.freeze({
 
   // In FB bundles, we preserve an inline require to ReactCurrentOwner.
   // See the explanation in FB version of ReactCurrentOwner in www:
-  'react/src/ReactCurrentOwner': (bundleType, entry) => {
+  './packages/react/src/ReactCurrentOwner.js': (bundleType, entry) => {
     switch (bundleType) {
       case FB_WWW_DEV:
       case FB_WWW_PROD:
       case FB_WWW_PROFILING:
-        return 'react/src/forks/ReactCurrentOwner.www.js';
+        return './packages/react/src/forks/ReactCurrentOwner.www.js';
       default:
         return null;
     }
@@ -206,41 +228,41 @@ const forks = Object.freeze({
 
   // Similarly, we preserve an inline require to ReactCurrentDispatcher.
   // See the explanation in FB version of ReactCurrentDispatcher in www:
-  'react/src/ReactCurrentDispatcher': (bundleType, entry) => {
+  './packages/react/src/ReactCurrentDispatcher.js': (bundleType, entry) => {
     switch (bundleType) {
       case FB_WWW_DEV:
       case FB_WWW_PROD:
       case FB_WWW_PROFILING:
-        return 'react/src/forks/ReactCurrentDispatcher.www.js';
+        return './packages/react/src/forks/ReactCurrentDispatcher.www.js';
       default:
         return null;
     }
   },
 
-  'react/src/ReactSharedInternals.js': (bundleType, entry) => {
+  './packages/react/src/ReactSharedInternals.js': (bundleType, entry) => {
     switch (bundleType) {
       case UMD_DEV:
       case UMD_PROD:
       case UMD_PROFILING:
-        return 'react/src/forks/ReactSharedInternals.umd.js';
+        return './packages/react/src/forks/ReactSharedInternals.umd.js';
       default:
         return null;
     }
   },
 
   // Different wrapping/reporting for caught errors.
-  'shared/invokeGuardedCallbackImpl': (bundleType, entry) => {
+  './packages/shared/invokeGuardedCallbackImpl.js': (bundleType, entry) => {
     switch (bundleType) {
       case FB_WWW_DEV:
       case FB_WWW_PROD:
       case FB_WWW_PROFILING:
-        return 'shared/forks/invokeGuardedCallbackImpl.www.js';
+        return './packages/shared/forks/invokeGuardedCallbackImpl.www.js';
       default:
         return null;
     }
   },
 
-  'react-reconciler/src/ReactFiberReconciler': (
+  './packages/react-reconciler/src/ReactFiberReconciler.js': (
     bundleType,
     entry,
     dependencies,
@@ -253,14 +275,14 @@ const forks = Object.freeze({
         case FB_WWW_PROD:
         case FB_WWW_PROFILING:
           // Use the forked version of the reconciler
-          return 'react-reconciler/src/ReactFiberReconciler.new.js';
+          return './packages/react-reconciler/src/ReactFiberReconciler.new.js';
       }
     }
     // Otherwise, use the non-forked version.
-    return 'react-reconciler/src/ReactFiberReconciler.old.js';
+    return './packages/react-reconciler/src/ReactFiberReconciler.old.js';
   },
 
-  'react-reconciler/src/ReactEventPriorities': (
+  './packages/react-reconciler/src/ReactEventPriorities.js': (
     bundleType,
     entry,
     dependencies,
@@ -273,14 +295,14 @@ const forks = Object.freeze({
         case FB_WWW_PROD:
         case FB_WWW_PROFILING:
           // Use the forked version of the reconciler
-          return 'react-reconciler/src/ReactEventPriorities.new.js';
+          return './packages/react-reconciler/src/ReactEventPriorities.new.js';
       }
     }
     // Otherwise, use the non-forked version.
-    return 'react-reconciler/src/ReactEventPriorities.old.js';
+    return './packages/react-reconciler/src/ReactEventPriorities.old.js';
   },
 
-  'react-reconciler/src/ReactFiberHotReloading': (
+  './packages/react-reconciler/src/ReactFiberHotReloading.js': (
     bundleType,
     entry,
     dependencies,
@@ -293,21 +315,24 @@ const forks = Object.freeze({
         case FB_WWW_PROD:
         case FB_WWW_PROFILING:
           // Use the forked version of the reconciler
-          return 'react-reconciler/src/ReactFiberHotReloading.new.js';
+          return './packages/react-reconciler/src/ReactFiberHotReloading.new.js';
       }
     }
     // Otherwise, use the non-forked version.
-    return 'react-reconciler/src/ReactFiberHotReloading.old.js';
+    return './packages/react-reconciler/src/ReactFiberHotReloading.old.js';
   },
 
   // Different dialogs for caught errors.
-  'react-reconciler/src/ReactFiberErrorDialog': (bundleType, entry) => {
+  './packages/react-reconciler/src/ReactFiberErrorDialog.js': (
+    bundleType,
+    entry
+  ) => {
     switch (bundleType) {
       case FB_WWW_DEV:
       case FB_WWW_PROD:
       case FB_WWW_PROFILING:
         // Use the www fork which shows an error dialog.
-        return 'react-reconciler/src/forks/ReactFiberErrorDialog.www.js';
+        return './packages/react-reconciler/src/forks/ReactFiberErrorDialog.www.js';
       case RN_OSS_DEV:
       case RN_OSS_PROD:
       case RN_OSS_PROFILING:
@@ -318,7 +343,7 @@ const forks = Object.freeze({
           case 'react-native-renderer':
           case 'react-native-renderer/fabric':
             // Use the RN fork which plays well with redbox.
-            return 'react-reconciler/src/forks/ReactFiberErrorDialog.native.js';
+            return './packages/react-reconciler/src/forks/ReactFiberErrorDialog.native.js';
           default:
             return null;
         }
@@ -327,7 +352,7 @@ const forks = Object.freeze({
     }
   },
 
-  'react-reconciler/src/ReactFiberHostConfig': (
+  './packages/react-reconciler/src/ReactFiberHostConfig.js': (
     bundleType,
     entry,
     dependencies,
@@ -342,7 +367,7 @@ const forks = Object.freeze({
     // eslint-disable-next-line no-for-of-loops/no-for-of-loops
     for (let rendererInfo of inlinedHostConfigs) {
       if (rendererInfo.entryPoints.indexOf(entry) !== -1) {
-        return `react-reconciler/src/forks/ReactFiberHostConfig.${rendererInfo.shortName}.js`;
+        return `./packages/react-reconciler/src/forks/ReactFiberHostConfig.${rendererInfo.shortName}.js`;
       }
     }
     throw new Error(
@@ -352,7 +377,7 @@ const forks = Object.freeze({
     );
   },
 
-  'react-server/src/ReactServerStreamConfig': (
+  './packages/react-server/src/ReactServerStreamConfig.js': (
     bundleType,
     entry,
     dependencies,
@@ -370,7 +395,7 @@ const forks = Object.freeze({
         if (!rendererInfo.isServerSupported) {
           return null;
         }
-        return `react-server/src/forks/ReactServerStreamConfig.${rendererInfo.shortName}.js`;
+        return `./packages/react-server/src/forks/ReactServerStreamConfig.${rendererInfo.shortName}.js`;
       }
     }
     throw new Error(
@@ -380,7 +405,7 @@ const forks = Object.freeze({
     );
   },
 
-  'react-server/src/ReactServerFormatConfig': (
+  './packages/react-server/src/ReactServerFormatConfig.js': (
     bundleType,
     entry,
     dependencies,
@@ -398,7 +423,7 @@ const forks = Object.freeze({
         if (!rendererInfo.isServerSupported) {
           return null;
         }
-        return `react-server/src/forks/ReactServerFormatConfig.${rendererInfo.shortName}.js`;
+        return `./packages/react-server/src/forks/ReactServerFormatConfig.${rendererInfo.shortName}.js`;
       }
     }
     throw new Error(
@@ -408,7 +433,7 @@ const forks = Object.freeze({
     );
   },
 
-  'react-server/src/ReactFlightServerConfig': (
+  './packages/react-server/src/ReactFlightServerConfig.js': (
     bundleType,
     entry,
     dependencies,
@@ -426,7 +451,7 @@ const forks = Object.freeze({
         if (!rendererInfo.isServerSupported) {
           return null;
         }
-        return `react-server/src/forks/ReactFlightServerConfig.${rendererInfo.shortName}.js`;
+        return `./packages/react-server/src/forks/ReactFlightServerConfig.${rendererInfo.shortName}.js`;
       }
     }
     throw new Error(
@@ -436,7 +461,7 @@ const forks = Object.freeze({
     );
   },
 
-  'react-client/src/ReactFlightClientHostConfig': (
+  './packages/react-client/src/ReactFlightClientHostConfig.js': (
     bundleType,
     entry,
     dependencies,
@@ -454,7 +479,7 @@ const forks = Object.freeze({
         if (!rendererInfo.isServerSupported) {
           return null;
         }
-        return `react-client/src/forks/ReactFlightClientHostConfig.${rendererInfo.shortName}.js`;
+        return `./packages/react-client/src/forks/ReactFlightClientHostConfig.${rendererInfo.shortName}.js`;
       }
     }
     throw new Error(
@@ -465,7 +490,7 @@ const forks = Object.freeze({
   },
 
   // We wrap top-level listeners into guards on www.
-  'react-dom/src/events/EventListener': (bundleType, entry) => {
+  './packages/react-dom/src/events/EventListener.js': (bundleType, entry) => {
     switch (bundleType) {
       case FB_WWW_DEV:
       case FB_WWW_PROD:
@@ -475,28 +500,34 @@ const forks = Object.freeze({
           return null;
         } else {
           // Use the www fork which is integrated with TimeSlice profiling.
-          return 'react-dom/src/events/forks/EventListener-www.js';
+          return './packages/react-dom/src/events/forks/EventListener-www.js';
         }
       default:
         return null;
     }
   },
 
-  'use-sync-external-store/src/useSyncExternalStore': (bundleType, entry) => {
+  './packages/use-sync-external-store/src/useSyncExternalStore.js': (
+    bundleType,
+    entry
+  ) => {
     if (entry.startsWith('use-sync-external-store/shim')) {
-      return 'use-sync-external-store/src/forks/useSyncExternalStore.forward-to-shim';
+      return './packages/use-sync-external-store/src/forks/useSyncExternalStore.forward-to-shim.js';
     }
     if (entry !== 'use-sync-external-store') {
       // Internal modules that aren't shims should use the native API from the
       // react package.
-      return 'use-sync-external-store/src/forks/useSyncExternalStore.forward-to-built-in';
+      return './packages/use-sync-external-store/src/forks/useSyncExternalStore.forward-to-built-in.js';
     }
     return null;
   },
 
-  'use-sync-external-store/src/isServerEnvironment': (bundleType, entry) => {
+  './packages/use-sync-external-store/src/isServerEnvironment.js': (
+    bundleType,
+    entry
+  ) => {
     if (entry.endsWith('.native')) {
-      return 'use-sync-external-store/src/forks/isServerEnvironment.native';
+      return './packages/use-sync-external-store/src/forks/isServerEnvironment.native.js';
     }
   },
 });
diff --git a/scripts/rollup/plugins/use-forks-plugin.js b/scripts/rollup/plugins/use-forks-plugin.js
index a645fa99c1b2..e3b261ff52b4 100644
--- a/scripts/rollup/plugins/use-forks-plugin.js
+++ b/scripts/rollup/plugins/use-forks-plugin.js
@@ -30,15 +30,19 @@ let resolveCache = new Map();
 function useForks(forks) {
   let resolvedForks = new Map();
   Object.keys(forks).forEach(srcModule => {
+    // Fork paths are relative to the project root. They must include the full
+    // path, including the extension. We intentionally don't use Node's module
+    // resolution algorithm because 1) require.resolve doesn't work with ESM
+    // modules, and 2) the behavior is easier to predict.
     const targetModule = forks[srcModule];
     resolvedForks.set(
-      require.resolve(srcModule),
+      path.resolve(process.cwd(), srcModule),
       // targetModule could be a string (a file path),
       // or an error (which we'd throw if it gets used).
       // Don't try to "resolve" errors, but cache
       // resolved file paths.
       typeof targetModule === 'string'
-        ? require.resolve(targetModule)
+        ? path.resolve(process.cwd(), targetModule)
         : targetModule
     );
   });