diff --git a/script/tool/lib/src/format_command.dart b/script/tool/lib/src/format_command.dart
index b5e6086..f93f221 100644
--- a/script/tool/lib/src/format_command.dart
+++ b/script/tool/lib/src/format_command.dart
@@ -11,7 +11,8 @@
 
 import 'common/core.dart';
 import 'common/output_utils.dart';
-import 'common/package_command.dart';
+import 'common/package_looping_command.dart';
+import 'common/repository_package.dart';
 
 /// In theory this should be 8191, but in practice that was still resulting in
 /// "The input line is too long" errors. This was chosen as a value that worked
@@ -40,7 +41,7 @@
     '/maven2/com/facebook/ktfmt/0.46/ktfmt-0.46-jar-with-dependencies.jar');
 
 /// A command to format all package code.
-class FormatCommand extends PackageCommand {
+class FormatCommand extends PackageLoopingCommand {
   /// Creates an instance of the format command.
   FormatCommand(
     super.packagesDir, {
@@ -85,18 +86,19 @@
       'to be in your path.';
 
   @override
-  Future<void> run() async {
+  Future<void> initializeRun() async {
     final String javaFormatterPath = await _getJavaFormatterPath();
     final String kotlinFormatterPath = await _getKotlinFormatterPath();
 
-    // This class is not based on PackageLoopingCommand because running the
-    // formatters separately for each package is an order of magnitude slower,
-    // due to the startup overhead of the formatters.
+    // All but Dart is formatted here rather than in runForPackage because
+    // running the formatters separately for each package is an order of
+    // magnitude slower, due to the startup overhead of the formatters.
+    //
+    // Dart has to be run per-package because the formatter can have different
+    // behavior based on the package's SDK, which can't be determined if the
+    // formatter isn't running in the context of the package.
     final Iterable<String> files =
         await _getFilteredFilePaths(getFiles(), relativeTo: packagesDir);
-    if (getBoolArg(_dartArg)) {
-      await _formatDart(files);
-    }
     if (getBoolArg(_javaArg)) {
       await _formatJava(files, javaFormatterPath);
     }
@@ -109,7 +111,28 @@
     if (getBoolArg(_swiftArg)) {
       await _formatAndLintSwift(files);
     }
+  }
 
+  @override
+  Future<PackageResult> runForPackage(RepositoryPackage package) async {
+    final Iterable<String> files = await _getFilteredFilePaths(
+      getFilesForPackage(package),
+      relativeTo: package.directory,
+    );
+    if (getBoolArg(_dartArg)) {
+      await _formatDart(files, workingDir: package.directory);
+    }
+    // Success or failure is determined overall in completeRun, since most code
+    // isn't being validated per-package, so just always return success at the
+    // package level.
+    // TODO(stuartmorgan): Consider doing _didModifyAnything checks per-package
+    //  instead, since the other languages are already formatted by the time
+    //  this code is being run.
+    return PackageResult.success();
+  }
+
+  @override
+  Future<void> completeRun() async {
     if (getBoolArg(_failonChangeArg)) {
       final bool modified = await _didModifyAnything();
       if (modified) {
@@ -291,13 +314,16 @@
     }
   }
 
-  Future<void> _formatDart(Iterable<String> files) async {
+  Future<void> _formatDart(
+    Iterable<String> files, {
+    Directory? workingDir,
+  }) async {
     final Iterable<String> dartFiles =
         _getPathsWithExtensions(files, <String>{'.dart'});
     if (dartFiles.isNotEmpty) {
       print('Formatting .dart files...');
-      final int exitCode =
-          await _runBatched('dart', <String>['format'], files: dartFiles);
+      final int exitCode = await _runBatched('dart', <String>['format'],
+          files: dartFiles, workingDir: workingDir);
       if (exitCode != 0) {
         printError('Failed to format Dart files: exit code $exitCode.');
         throw ToolExit(_exitFlutterFormatFailed);
@@ -440,11 +466,8 @@
   ///
   /// Returns the exit code of the first failure, which stops the run, or 0
   /// on success.
-  Future<int> _runBatched(
-    String command,
-    List<String> arguments, {
-    required Iterable<String> files,
-  }) async {
+  Future<int> _runBatched(String command, List<String> arguments,
+      {required Iterable<String> files, Directory? workingDir}) async {
     final int commandLineMax =
         platform.isWindows ? windowsCommandLineMax : nonWindowsCommandLineMax;
 
@@ -462,7 +485,7 @@
       batch.sort(); // For ease of testing.
       final int exitCode = await processRunner.runAndStream(
           command, <String>[...arguments, ...batch],
-          workingDir: packagesDir);
+          workingDir: workingDir ?? packagesDir);
       if (exitCode != 0) {
         return exitCode;
       }
diff --git a/script/tool/test/format_command_test.dart b/script/tool/test/format_command_test.dart
index 33f5104..b2c8237 100644
--- a/script/tool/test/format_command_test.dart
+++ b/script/tool/test/format_command_test.dart
@@ -63,15 +63,13 @@
   }
 
   /// Returns a list of [count] relative paths to pass to [createFakePlugin]
-  /// or [createFakePackage] with name [packageName] such that each path will
-  /// be 99 characters long relative to [packagesDir].
+  /// or [createFakePackage] such that each path will be 99 characters long
+  /// relative to the package directory.
   ///
   /// This is for each of testing batching, since it means each file will
   /// consume 100 characters of the batch length.
-  List<String> get99CharacterPathExtraFiles(String packageName, int count) {
-    final int padding = 99 -
-        packageName.length -
-        1 - // the path separator after the package name
+  List<String> get99CharacterPathExtraFiles(int count) {
+    const int padding = 99 -
         1 - // the path separator after the padding
         10; // the file name
     const int filenameBase = 10000;
@@ -100,10 +98,7 @@
     expect(
         processRunner.recordedCalls,
         orderedEquals(<ProcessCall>[
-          ProcessCall(
-              'dart',
-              <String>['format', ...getPackagesDirRelativePaths(plugin, files)],
-              packagesDir.path),
+          ProcessCall('dart', const <String>['format', ...files], plugin.path),
         ]));
   });
 
@@ -135,12 +130,7 @@
         processRunner.recordedCalls,
         orderedEquals(<ProcessCall>[
           ProcessCall(
-              'dart',
-              <String>[
-                'format',
-                ...getPackagesDirRelativePaths(plugin, formattedFiles)
-              ],
-              packagesDir.path),
+              'dart', const <String>['format', ...formattedFiles], plugin.path),
         ]));
   });
 
@@ -719,12 +709,7 @@
               ],
               packagesDir.path),
           ProcessCall(
-              'dart',
-              <String>[
-                'format',
-                ...getPackagesDirRelativePaths(plugin, dartFiles)
-              ],
-              packagesDir.path),
+              'dart', const <String>['format', ...dartFiles], plugin.path),
           ProcessCall(
               'java',
               <String>[
@@ -899,11 +884,10 @@
     const int batchSize = (windowsCommandLineMax ~/ 100) - 1;
 
     // Make the file list one file longer than would fit in the batch.
-    final List<String> batch1 =
-        get99CharacterPathExtraFiles(pluginName, batchSize + 1);
+    final List<String> batch1 = get99CharacterPathExtraFiles(batchSize + 1);
     final String extraFile = batch1.removeLast();
 
-    createFakePlugin(
+    final RepositoryPackage package = createFakePlugin(
       pluginName,
       packagesDir,
       extraFiles: <String>[...batch1, extraFile],
@@ -921,9 +905,9 @@
               'dart',
               <String>[
                 'format',
-                '$pluginName\\$extraFile',
+                extraFile,
               ],
-              packagesDir.path),
+              package.path),
         ));
   });
 
@@ -936,8 +920,7 @@
     const int batchSize = (windowsCommandLineMax ~/ 100) - 1;
 
     // Make the file list one file longer than would fit in a Windows batch.
-    final List<String> batch =
-        get99CharacterPathExtraFiles(pluginName, batchSize + 1);
+    final List<String> batch = get99CharacterPathExtraFiles(batchSize + 1);
 
     createFakePlugin(
       pluginName,
@@ -956,11 +939,10 @@
     const int batchSize = (nonWindowsCommandLineMax ~/ 100) - 1;
 
     // Make the file list one file longer than would fit in the batch.
-    final List<String> batch1 =
-        get99CharacterPathExtraFiles(pluginName, batchSize + 1);
+    final List<String> batch1 = get99CharacterPathExtraFiles(batchSize + 1);
     final String extraFile = batch1.removeLast();
 
-    createFakePlugin(
+    final RepositoryPackage package = createFakePlugin(
       pluginName,
       packagesDir,
       extraFiles: <String>[...batch1, extraFile],
@@ -978,9 +960,9 @@
               'dart',
               <String>[
                 'format',
-                '$pluginName/$extraFile',
+                extraFile,
               ],
-              packagesDir.path),
+              package.path),
         ));
   });
 }