diff --git a/packages/metro/src/DeltaBundler/Serializers/__tests__/getAllFiles-test.js b/packages/metro/src/DeltaBundler/Serializers/__tests__/getAllFiles-test.js
index 1c1989a6e0..d7fc9e7f7c 100644
--- a/packages/metro/src/DeltaBundler/Serializers/__tests__/getAllFiles-test.js
+++ b/packages/metro/src/DeltaBundler/Serializers/__tests__/getAllFiles-test.js
@@ -102,6 +102,25 @@ describe('getOrderedDependencyPaths', () => {
     ]);
   });
 
+  test('Should exclude virtual modules, which have no file', async () => {
+    const jsOutput = [
+      {
+        type: 'js/module',
+        data: {code: '//', lineCount: 1, map: [], functionMap: null},
+      },
+    ];
+    const graph = {
+      dependencies: new Map([
+        [1, {path: '/tmp/1.js', output: jsOutput}],
+        [2, {path: 'virtual:/tmp/1.generated.js', output: jsOutput}],
+      ]),
+    };
+
+    expect(
+      await getAllFiles([], graph, {processModuleFilter: () => true}),
+    ).toEqual(['/tmp/1.js']);
+  });
+
   test('Should add assets data dependencies correctly', async () => {
     const graph = {
       dependencies: new Map([
diff --git a/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js b/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js
index 17f9f52b8f..46683c21c4 100644
--- a/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js
+++ b/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js
@@ -184,3 +184,33 @@ Object {
 }
 `);
 });
+
+test('gives a virtual module anchored at a real file URLs distinct from that file', () => {
+  const virtualFooModule: Module<> = {
+    ...fooModule,
+    path: 'virtual:/root/foo',
+    dependencies: new Map(),
+  };
+  const {added} = hmrJSBundle(
+    {
+      added: new Map([
+        ['root/foo', fooModule],
+        ['virtual:/root/foo', virtualFooModule],
+      ]),
+      modified: new Map(),
+      deleted: new Set(),
+      reset: false,
+    },
+    graph,
+    options,
+  );
+  expect(
+    added.map(({sourceURL, sourceMappingURL}) => [sourceURL, sourceMappingURL]),
+  ).toEqual([
+    ['http://localhost/foo.bundle', 'http://localhost/foo.map'],
+    [
+      'http://localhost/foo.bundle//&virtual=true',
+      'http://localhost/foo.map?virtual=true',
+    ],
+  ]);
+});
diff --git a/packages/metro/src/DeltaBundler/Serializers/getAllFiles.js b/packages/metro/src/DeltaBundler/Serializers/getAllFiles.js
index a729384311..ae86013dd9 100644
--- a/packages/metro/src/DeltaBundler/Serializers/getAllFiles.js
+++ b/packages/metro/src/DeltaBundler/Serializers/getAllFiles.js
@@ -12,6 +12,7 @@
 import type {Module, ReadOnlyGraph} from '../types';
 
 import {getAssetFiles} from '../../Assets';
+import {isVirtualModulePath} from '../../lib/modulePath';
 import {getJsOutput, isJsModule} from './helpers/js';
 
 type Options = {
@@ -36,7 +37,12 @@ export default async function getAllFiles(
   }
 
   for (const module of modules.values()) {
-    if (!isJsModule(module) || !processModuleFilter(module)) {
+    if (
+      !isJsModule(module) ||
+      !processModuleFilter(module) ||
+      // A virtual module has no file.
+      isVirtualModulePath(module.path)
+    ) {
       continue;
     }
 
diff --git a/packages/metro/src/DeltaBundler/Serializers/helpers/__tests__/js-test.js b/packages/metro/src/DeltaBundler/Serializers/helpers/__tests__/js-test.js
index d1a396ab6a..648ae7a1c9 100644
--- a/packages/metro/src/DeltaBundler/Serializers/helpers/__tests__/js-test.js
+++ b/packages/metro/src/DeltaBundler/Serializers/helpers/__tests__/js-test.js
@@ -156,6 +156,49 @@ describe('wrapModule()', () => {
     );
   });
 
+  test('names a virtual module by its virtual path, in its own namespace', () => {
+    expect(
+      raw(
+        wrapModule(
+          {...myModule, path: 'virtual:' + p('/root/foo.js')},
+          {
+            createModuleId: createModuleIdFactory(),
+            dev: true,
+            includeAsyncPaths: false,
+            projectRoot: p('/root'),
+            serverRoot: p('/root'),
+            sourceUrl: null,
+          },
+        ),
+      ),
+    ).toMatchInlineSnapshot(
+      `__d(function() { console.log("foo") },0,[1,2],"virtual:foo.js");`,
+    );
+  });
+
+  test('marks the path of an async virtual dependency as virtual', () => {
+    const dep = nullthrows(myModule.dependencies.get('bar'));
+    myModule.dependencies.set('bar', {
+      ...dep,
+      absolutePath: 'virtual:' + p('/root/bar.js'),
+      data: {...dep.data, data: {...dep.data.data, asyncType: 'async'}},
+    });
+    expect(
+      raw(
+        wrapModule(myModule, {
+          createModuleId: createModuleIdFactory(),
+          dev: false,
+          includeAsyncPaths: true,
+          projectRoot: p('/root'),
+          serverRoot: p('/root'),
+          sourceUrl: 'http://localhost/Main.bundle?param1=true',
+        }),
+      ),
+    ).toMatchInlineSnapshot(
+      `__d(function() { console.log("foo") },0,{"0":1,"1":2,"paths":{"1":"/bar.bundle?param1=true&modulesOnly=true&runModule=false&virtual=true"}});`,
+    );
+  });
+
   test('async dependency paths respect serverRoot', () => {
     const dep = nullthrows(myModule.dependencies.get('bar'));
     myModule.dependencies.set('bar', {
diff --git a/packages/metro/src/DeltaBundler/Serializers/helpers/js.js b/packages/metro/src/DeltaBundler/Serializers/helpers/js.js
index 68900741f7..689788ca73 100644
--- a/packages/metro/src/DeltaBundler/Serializers/helpers/js.js
+++ b/packages/metro/src/DeltaBundler/Serializers/helpers/js.js
@@ -18,6 +18,12 @@ import type {
 import type {JsOutput} from 'metro-transform-worker';
 
 import {isResolvedDependency} from '../../../lib/isResolvedDependency';
+import {
+  VIRTUAL_MODULE_URL_PARAM,
+  getModuleDisplayPath,
+  getModuleSourcePath,
+  isVirtualModulePath,
+} from '../../../lib/modulePath';
 import {normalizePathSeparatorsToPosix} from '../../../lib/pathUtils';
 import invariant from 'invariant';
 import * as jscSafeUrl from 'jsc-safe-url';
@@ -78,9 +84,7 @@ export function wrapModule(module: Module<>, options: Options): string {
 function getModuleVerboseName(module: Module<>, options: Options): string {
   // The relative path of the module, to make debugging easier. This is mapped
   // to `module.verboseName` in `require.js`.
-  return normalizePathSeparatorsToPosix(
-    path.relative(options.projectRoot, module.path),
-  );
+  return getModuleDisplayPath(module.path, options.projectRoot);
 }
 
 // Default value stored in the `__d(...)` `paths` object for an async
@@ -104,8 +108,14 @@ function getDefaultAsyncDependencyPath(
   const {searchParams} = new URL(jscSafeUrl.toNormalUrl(options.sourceUrl));
   searchParams.set('modulesOnly', 'true');
   searchParams.set('runModule', 'false');
+  if (isVirtualModulePath(dependency.absolutePath)) {
+    searchParams.set(VIRTUAL_MODULE_URL_PARAM, 'true');
+  }
 
-  const bundlePath = path.relative(options.serverRoot, dependency.absolutePath);
+  const bundlePath = path.relative(
+    options.serverRoot,
+    getModuleSourcePath(dependency.absolutePath),
+  );
   return (
     '/' +
     normalizePathSeparatorsToPosix(
diff --git a/packages/metro/src/DeltaBundler/Serializers/hmrJSBundle.js b/packages/metro/src/DeltaBundler/Serializers/hmrJSBundle.js
index 958a27fd9b..dbb0babe34 100644
--- a/packages/metro/src/DeltaBundler/Serializers/hmrJSBundle.js
+++ b/packages/metro/src/DeltaBundler/Serializers/hmrJSBundle.js
@@ -12,6 +12,11 @@
 import type {DeltaResult, Module, ReadOnlyGraph} from '../types';
 import type {HmrModule} from 'metro-runtime/src/modules/types';
 
+import {
+  VIRTUAL_MODULE_URL_PARAM,
+  getModuleSourcePath,
+  isVirtualModulePath,
+} from '../../lib/modulePath';
 import {isJsModule, wrapModule} from './helpers/js';
 import debugModule from 'debug';
 import * as jscSafeUrl from 'jsc-safe-url';
@@ -38,14 +43,15 @@ function generateModules(
 
   for (const module of sourceModules) {
     if (isJsModule(module)) {
+      const sourcePath = getModuleSourcePath(module.path);
       const getPathname = (extension: 'bundle' | 'map') => {
         return (
           path
             .relative(
               options.serverRoot ?? options.projectRoot,
               path.join(
-                path.dirname(module.path),
-                path.basename(module.path, path.extname(module.path)) +
+                path.dirname(sourcePath),
+                path.basename(sourcePath, path.extname(sourcePath)) +
                   '.' +
                   extension,
               ),
@@ -59,6 +65,9 @@ function generateModules(
 
       const clientUrl = new URL(options.clientUrl);
       clientUrl.searchParams.delete('excludeSource');
+      if (isVirtualModulePath(module.path)) {
+        clientUrl.searchParams.set(VIRTUAL_MODULE_URL_PARAM, 'true');
+      }
 
       clientUrl.pathname = getPathname('map');
       const sourceMappingURL = clientUrl.toString();
diff --git a/packages/metro/src/Server.js b/packages/metro/src/Server.js
index 28e3a1c443..0bde1b29cd 100644
--- a/packages/metro/src/Server.js
+++ b/packages/metro/src/Server.js
@@ -56,6 +56,12 @@ import {calculateBundleProgressRatio} from './lib/bundleProgressUtils';
 import bundleToString from './lib/bundleToString';
 import formatBundlingError from './lib/formatBundlingError';
 import getGraphId from './lib/getGraphId';
+import {
+  VIRTUAL_MODULE_URL_PARAM,
+  getModuleSourcePath,
+  isVirtualModulePath,
+  isVirtualModuleUrl,
+} from './lib/modulePath';
 import parseBundleOptionsFromBundleRequestUrl from './lib/parseBundleOptionsFromBundleRequestUrl';
 import parseJsonBody from './lib/parseJsonBody';
 import RootUrlMap from './lib/RootUrlMap';
@@ -705,7 +711,8 @@ export default class Server {
     } else {
       const sourceFilePath =
         this._rootUrlMap.filePathOfUrlDecodedPathname(filePathname);
-      if (sourceFilePath != null) {
+      // Virtual modules aren't served by URL yet.
+      if (sourceFilePath != null && !isVirtualModuleUrl(urlObj.searchParams)) {
         await this._processSourceRequest(sourceFilePath, res);
       } else {
         next();
@@ -1750,8 +1757,14 @@ export default class Server {
   // eslint-disable-next-line consistent-return
   _getModuleSourceUrl(module: Module<>, mode: SourcePathsMode): string {
     switch (mode) {
-      case SourcePathsMode.ServerUrl:
-        return this._rootUrlMap.urlPathnameOfFilePath(module.path);
+      case SourcePathsMode.ServerUrl: {
+        const pathname = this._rootUrlMap.urlPathnameOfFilePath(
+          getModuleSourcePath(module.path),
+        );
+        return isVirtualModulePath(module.path)
+          ? `${pathname}?${VIRTUAL_MODULE_URL_PARAM}=true`
+          : pathname;
+      }
       case SourcePathsMode.Absolute:
         return module.path;
     }
diff --git a/packages/metro/src/Server/__tests__/Server-test.js b/packages/metro/src/Server/__tests__/Server-test.js
index 882202892f..72ba785c50 100644
--- a/packages/metro/src/Server/__tests__/Server-test.js
+++ b/packages/metro/src/Server/__tests__/Server-test.js
@@ -27,6 +27,7 @@ import {posixToSystemPath as p} from 'metro-resolver/private/__tests__/utils';
 import MockRequest from 'mock-req';
 // $FlowFixMe[untyped-import]
 import MockResponse from 'mock-res';
+import nullthrows from 'nullthrows';
 
 const {
   getDefaultConfig: {getDefaultValues},
@@ -802,6 +803,32 @@ describe('processRequest', () => {
     });
   });
 
+  test('marks the url-server source path of a virtual module', async () => {
+    // $FlowFixMe[prop-missing] Missing from the flow-typed Jest definitions.
+    const buildGraphImpl = buildGraph.getMockImplementation();
+    buildGraph.mockImplementationOnce(async (...args) => {
+      const graph = await buildGraphImpl(...args);
+      // A virtual module at the path of a real one.
+      dependencies.set('virtual:' + p('/root/foo.js'), {
+        ...nullthrows(dependencies.get(p('/root/foo.js'))),
+        path: 'virtual:' + p('/root/foo.js'),
+        getSource: () => Buffer.from('code-virtual'),
+      });
+      return graph;
+    });
+
+    const response = await makeRequest('mybundle.map?sourcePaths=url-server');
+
+    expect(
+      response._getJSON().sections.map(section => section.map.sources),
+    ).toEqual([
+      ['/require-js'],
+      ['/[metro-project]/mybundle.js'],
+      ['/[metro-project]/foo.js'],
+      ['/[metro-project]/foo.js?virtual=true'],
+    ]);
+  });
+
   test('passes in the unstable_transformProfile param', async () => {
     await makeRequest('index.bundle?unstable_transformProfile=hermes-stable');
 
@@ -1097,6 +1124,13 @@ describe('processRequest', () => {
 
       expect(response.getHeader('content-type')).toBe('image/png');
     });
+
+    test('does not serve a file for a virtual module at its path', async () => {
+      // The request is passed on to the next handler, with no error.
+      await expect(
+        makeRequest('/[metro-project]/foo.js?virtual=true'),
+      ).rejects.toBeUndefined();
+    });
   });
 
   describe('build(options)', () => {
diff --git a/packages/metro/src/lib/__tests__/modulePath-test.js b/packages/metro/src/lib/__tests__/modulePath-test.js
new file mode 100644
index 0000000000..0f9865fafc
--- /dev/null
+++ b/packages/metro/src/lib/__tests__/modulePath-test.js
@@ -0,0 +1,51 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ * @oncall react_native
+ */
+
+'use strict';
+
+import {
+  deriveVirtualModulePath,
+  getModuleDisplayPath,
+  getModuleSourcePath,
+  isVirtualModulePath,
+  isVirtualModuleUrl,
+} from '../modulePath';
+
+test('a virtual module path is the virtual path in the virtual namespace', () => {
+  const modulePath = deriveVirtualModulePath('/root/App.generated.tsx');
+  expect(modulePath).toBe('virtual:/root/App.generated.tsx');
+  expect(isVirtualModulePath(modulePath)).toBe(true);
+  expect(getModuleSourcePath(modulePath)).toBe('/root/App.generated.tsx');
+});
+
+test('real module paths pass through unchanged', () => {
+  expect(isVirtualModulePath('/root/App.tsx')).toBe(false);
+  expect(getModuleSourcePath('/root/App.tsx')).toBe('/root/App.tsx');
+  expect(getModuleDisplayPath('/root/src/App.tsx', '/root')).toBe(
+    'src/App.tsx',
+  );
+});
+
+test('a virtual module is displayed relative to the root, in its namespace', () => {
+  expect(
+    getModuleDisplayPath('virtual:/root/src/App.generated.tsx', '/root'),
+  ).toBe('virtual:src/App.generated.tsx');
+});
+
+test.each([
+  ['?virtual=true', true],
+  ['?platform=ios&virtual=true', true],
+  ['?virtual', true],
+  ['?platform=ios', false],
+  ['', false],
+])('isVirtualModuleUrl(%s) is %s', (search, expected) => {
+  expect(isVirtualModuleUrl(new URLSearchParams(search))).toBe(expected);
+});
diff --git a/packages/metro/src/lib/__tests__/parseBundleOptionsFromBundleRequestUrl-test.js b/packages/metro/src/lib/__tests__/parseBundleOptionsFromBundleRequestUrl-test.js
index c7e709c659..48d0d669ea 100644
--- a/packages/metro/src/lib/__tests__/parseBundleOptionsFromBundleRequestUrl-test.js
+++ b/packages/metro/src/lib/__tests__/parseBundleOptionsFromBundleRequestUrl-test.js
@@ -47,6 +47,15 @@ describe('parseBundleOptionsFromBundleRequestUrl', () => {
     );
   });
 
+  test('rejects a virtual module URL', () => {
+    expect(() =>
+      parseBundleOptionsFromBundleRequestUrl(
+        'http://localhost/App.bundle?platform=ios&virtual=true',
+        new Set(['ios']),
+      ),
+    ).toThrowError('Virtual modules cannot be requested by URL yet.');
+  });
+
   test.each(['absolute', 'relative'])(
     '%s protocol urls- infers the source url and source map url from the pathname',
     type => {
diff --git a/packages/metro/src/lib/modulePath.js b/packages/metro/src/lib/modulePath.js
new file mode 100644
index 0000000000..ff601947da
--- /dev/null
+++ b/packages/metro/src/lib/modulePath.js
@@ -0,0 +1,78 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ * @oncall react_native
+ */
+
+import {normalizePathSeparatorsToPosix} from './pathUtils';
+import path from 'node:path';
+
+/**
+ * The namespace of virtual module paths in the graph. A virtual module's path
+ * is this prefix followed by its absolute virtual path, so it can never equal
+ * the absolute path of a real file, and anything that mistakes it for one
+ * fails rather than reading the wrong file.
+ */
+const VIRTUAL_MODULE_NAMESPACE = 'virtual:';
+
+/**
+ * The URL search parameter that marks a virtual module. A virtual module's URL
+ * is the one a file at its virtual path would have, plus this parameter.
+ */
+export const VIRTUAL_MODULE_URL_PARAM = 'virtual';
+
+/**
+ * The graph path of the virtual module at `virtualPath`. A virtual path names
+ * exactly one module: the same virtual path with different source is a
+ * modification of that module, as an edit to a file is.
+ */
+export function deriveVirtualModulePath(virtualPath: string): string {
+  return VIRTUAL_MODULE_NAMESPACE + virtualPath;
+}
+
+export function isVirtualModulePath(modulePath: string): boolean {
+  return modulePath.startsWith(VIRTUAL_MODULE_NAMESPACE);
+}
+
+/**
+ * The path a module is resolved from, transformed as, and addressed by in
+ * URLs. For a virtual module this is its virtual path, so imports inside it
+ * resolve from that path's directory and path-based transform configuration,
+ * extension checks included, behaves as for a file at that path. Otherwise it
+ * is the module path itself.
+ */
+export function getModuleSourcePath(modulePath: string): string {
+  return isVirtualModulePath(modulePath)
+    ? modulePath.slice(VIRTUAL_MODULE_NAMESPACE.length)
+    : modulePath;
+}
+
+/**
+ * A module path for display, as in development module names: relative to
+ * `rootDir` with POSIX separators, and namespaced if the module is virtual.
+ */
+export function getModuleDisplayPath(
+  modulePath: string,
+  rootDir: string,
+): string {
+  const relativePath = normalizePathSeparatorsToPosix(
+    path.relative(rootDir, getModuleSourcePath(modulePath)),
+  );
+  return isVirtualModulePath(modulePath)
+    ? VIRTUAL_MODULE_NAMESPACE + relativePath
+    : relativePath;
+}
+
+/**
+ * Whether a URL addresses a virtual module. Its path is the module's virtual
+ * path, which may also be a real file's, so such a URL must never be served as
+ * that file.
+ */
+export function isVirtualModuleUrl(searchParams: URLSearchParams): boolean {
+  return searchParams.has(VIRTUAL_MODULE_URL_PARAM);
+}
diff --git a/packages/metro/src/lib/parseBundleOptionsFromBundleRequestUrl.js b/packages/metro/src/lib/parseBundleOptionsFromBundleRequestUrl.js
index 2e13cf101d..8e0612deb1 100644
--- a/packages/metro/src/lib/parseBundleOptionsFromBundleRequestUrl.js
+++ b/packages/metro/src/lib/parseBundleOptionsFromBundleRequestUrl.js
@@ -14,6 +14,7 @@ import type {TransformProfile} from 'metro-babel-transformer';
 
 import parsePlatformFilePath from '../node-haste/lib/parsePlatformFilePath';
 import {SourcePathsMode} from '../shared/types';
+import {isVirtualModuleUrl} from './modulePath';
 import parseCustomResolverOptions from './parseCustomResolverOptions';
 import parseCustomTransformOptions from './parseCustomTransformOptions';
 import debugModule from 'debug';
@@ -70,6 +71,12 @@ export default function parseBundleOptionsFromBundleRequestUrl(
     hash,
   } = new URL(rawNonJscSafeUrlEncodedUrl, RESOLVE_BASE_URL /* baseURL */);
 
+  if (isVirtualModuleUrl(searchParams)) {
+    throw new Error('Virtual modules cannot be requested by URL yet.', {
+      cause: rawNonJscSafeUrlEncodedUrl,
+    });
+  }
+
   // e.g. "//localhost:8081/foo/bar.js?platform=ios"
   const isRelativeProtocol = rawNonJscSafeUrlEncodedUrl.startsWith('//');