diff --git a/script/tool/lib/src/update_excerpts_command.dart b/script/tool/lib/src/update_excerpts_command.dart
index 8583e4993c7..d50082377f8 100644
--- a/script/tool/lib/src/update_excerpts_command.dart
+++ b/script/tool/lib/src/update_excerpts_command.dart
@@ -15,7 +15,7 @@ import 'common/package_looping_command.dart';
 import 'common/process_runner.dart';
 import 'common/repository_package.dart';
 
-/// A command to update README code excerpts from code files.
+/// A command to update .md code excerpts from code files.
 class UpdateExcerptsCommand extends PackageLoopingCommand {
   /// Creates a excerpt updater command instance.
   UpdateExcerptsCommand(
@@ -51,7 +51,7 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
   final String name = 'update-excerpts';
 
   @override
-  final String description = 'Updates code excerpts in README.md files, based '
+  final String description = 'Updates code excerpts in .md files, based '
       'on code from code files, via code-excerpt';
 
   @override
@@ -105,13 +105,16 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
     }
 
     if (getBoolArg(_failOnChangeFlag)) {
-      final String? stateError = await _validateRepositoryState();
+      final String? stateError = await _validateRepositoryState(package);
       if (stateError != null) {
-        printError('README.md is out of sync with its source excerpts.\n\n'
-            'If you edited code in README.md directly, you should instead edit '
-            'the example source files. If you edited source files, run the '
-            'repository tooling\'s "$name" command on this package, and update '
-            'your PR with the resulting changes.');
+        printError('One or more .md files are out of sync with their source '
+            'excerpts.\n\n'
+            'If you edited code in a .md file directly, you should instead '
+            'edit the example source files. If you edited source files, run '
+            'the repository tooling\'s "$name" command on this package, and '
+            'update your PR with the resulting changes.\n\n'
+            'For more information, see '
+            'https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#readme-code');
         return PackageResult.fail(<String>[stateError]);
       }
     }
@@ -138,14 +141,24 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
     return exitCode == 0;
   }
 
-  /// Runs the injection step to update [targetPackage]'s README with the latest
-  /// excerpts from [example], returning true on success.
+  /// Runs the injection step to update [targetPackage]'s top-level .md files
+  /// with the latest excerpts from [example], returning true on success.
   Future<bool> _injectSnippets(
     RepositoryPackage example, {
     required RepositoryPackage targetPackage,
   }) async {
-    final String relativeReadmePath =
-        getRelativePosixPath(targetPackage.readmeFile, from: example.directory);
+    final List<String> relativeMdPaths = targetPackage.directory
+        .listSync()
+        .whereType<File>()
+        .where((File f) =>
+            f.basename.toLowerCase().endsWith('.md') &&
+            // Exclude CHANGELOG since it should never have excerpts.
+            f.basename != 'CHANGELOG.md')
+        .map((File f) => getRelativePosixPath(f, from: example.directory))
+        .toList();
+    if (relativeMdPaths.isEmpty) {
+      return true;
+    }
     final int exitCode = await processRunner.runAndStream(
         'dart',
         <String>[
@@ -154,7 +167,7 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
           '--write-in-place',
           '--yaml',
           '--no-escape-ng-interpolation',
-          relativeReadmePath,
+          ...relativeMdPaths,
         ],
         workingDir: example.directory);
     return exitCode == 0;
@@ -212,11 +225,11 @@ class UpdateExcerptsCommand extends PackageLoopingCommand {
 
   /// Checks the git state, returning an error string if any .md files have
   /// changed.
-  Future<String?> _validateRepositoryState() async {
+  Future<String?> _validateRepositoryState(RepositoryPackage package) async {
     final io.ProcessResult checkFiles = await processRunner.run(
       'git',
       <String>['ls-files', '--modified'],
-      workingDir: packagesDir,
+      workingDir: package.directory,
       logOnError: true,
     );
     if (checkFiles.exitCode != 0) {
diff --git a/script/tool/test/update_excerpts_command_test.dart b/script/tool/test/update_excerpts_command_test.dart
index 7bb0297de13..09862b3b321 100644
--- a/script/tool/test/update_excerpts_command_test.dart
+++ b/script/tool/test/update_excerpts_command_test.dart
@@ -111,7 +111,7 @@ void main() {
 
   test('updates example readme when config is present', () async {
     final RepositoryPackage package = createFakePlugin('a_package', packagesDir,
-        extraFiles: <String>[kReadmeExcerptConfigPath]);
+        extraFiles: <String>[kReadmeExcerptConfigPath, 'example/README.md']);
     final Directory example = getExampleDir(package);
 
     final List<String> output =
@@ -153,6 +153,52 @@ void main() {
         ]));
   });
 
+  test('includes all top-level .md files', () async {
+    const String otherMdFileName = 'another_file.md';
+    final RepositoryPackage package = createFakePlugin('a_package', packagesDir,
+        extraFiles: <String>[kReadmeExcerptConfigPath, otherMdFileName]);
+    final Directory example = getExampleDir(package);
+
+    final List<String> output =
+        await runCapturingPrint(runner, <String>['update-excerpts']);
+
+    expect(
+        processRunner.recordedCalls,
+        containsAll(<ProcessCall>[
+          ProcessCall(
+              'dart',
+              const <String>[
+                'run',
+                'build_runner',
+                'build',
+                '--config',
+                'excerpt',
+                '--output',
+                'excerpts',
+                '--delete-conflicting-outputs',
+              ],
+              example.path),
+          ProcessCall(
+              'dart',
+              const <String>[
+                'run',
+                'code_excerpt_updater',
+                '--write-in-place',
+                '--yaml',
+                '--no-escape-ng-interpolation',
+                '../README.md',
+                '../$otherMdFileName',
+              ],
+              example.path),
+        ]));
+
+    expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Ran for 1 package(s)'),
+        ]));
+  });
+
   test('skips when no config is present', () async {
     createFakePlugin('a_package', packagesDir);
 
@@ -277,7 +323,7 @@ void main() {
 
   test('fails if example injection fails', () async {
     createFakePlugin('a_package', packagesDir,
-        extraFiles: <String>[kReadmeExcerptConfigPath]);
+        extraFiles: <String>[kReadmeExcerptConfigPath, 'example/README.md']);
 
     processRunner.mockProcessesForExecutable['dart'] = <FakeProcessInfo>[
       FakeProcessInfo(MockProcess(), <String>['pub', 'get']),
@@ -307,7 +353,7 @@ void main() {
     createFakePlugin('a_plugin', packagesDir,
         extraFiles: <String>[kReadmeExcerptConfigPath]);
 
-    const String changedFilePath = 'packages/a_plugin/README.md';
+    const String changedFilePath = 'README.md';
     processRunner.mockProcessesForExecutable['git'] = <FakeProcessInfo>[
       FakeProcessInfo(MockProcess(stdout: changedFilePath)),
     ];
@@ -323,9 +369,10 @@ void main() {
     expect(
         output,
         containsAllInOrder(<Matcher>[
-          contains('README.md is out of sync with its source excerpts'),
+          contains(
+              'One or more .md files are out of sync with their source excerpts'),
           contains('Snippets are out of sync in the following files: '
-              'packages/a_plugin/README.md'),
+              '$changedFilePath'),
         ]));
   });