diff --git a/packages/flutter/lib/src/services/raw_keyboard.dart b/packages/flutter/lib/src/services/raw_keyboard.dart
index 0184c9054e..a0d8245cb2 100644
--- a/packages/flutter/lib/src/services/raw_keyboard.dart
+++ b/packages/flutter/lib/src/services/raw_keyboard.dart
@@ -284,7 +284,7 @@ abstract class RawKeyEvent with Diagnosticable {
 
   /// Creates a concrete [RawKeyEvent] class from a message in the form received
   /// on the [SystemChannels.keyEvent] channel.
-  factory RawKeyEvent.fromMessage(Map<String, dynamic> message) {
+  factory RawKeyEvent.fromMessage(Map<String, Object?> message) {
     String? character;
     RawKeyEventData _dataFromWeb() {
       final String? key = message['key'] as String?;
@@ -303,7 +303,7 @@ abstract class RawKeyEvent with Diagnosticable {
     if (kIsWeb) {
       data = _dataFromWeb();
     } else {
-      final String keymap = message['keymap'] as String;
+      final String keymap = message['keymap']! as String;
       switch (keymap) {
         case 'android':
           data = RawKeyEventDataAndroid(
@@ -388,7 +388,7 @@ abstract class RawKeyEvent with Diagnosticable {
           throw FlutterError('Unknown keymap for key events: $keymap');
       }
     }
-    final String type = message['type'] as String;
+    final String type = message['type']! as String;
     switch (type) {
       case 'keydown':
         return RawKeyDownEvent(data: data, character: character);
diff --git a/packages/flutter/lib/src/services/system_channels.dart b/packages/flutter/lib/src/services/system_channels.dart
index 49af63f230..582daee3d4 100644
--- a/packages/flutter/lib/src/services/system_channels.dart
+++ b/packages/flutter/lib/src/services/system_channels.dart
@@ -240,7 +240,7 @@ class SystemChannels {
   ///  * [RawKeyboard], which uses this channel to expose key data.
   ///  * [new RawKeyEvent.fromMessage], which can decode this data into the [RawKeyEvent]
   ///    subclasses mentioned above.
-  static const BasicMessageChannel<dynamic> keyEvent = BasicMessageChannel<dynamic>(
+  static const BasicMessageChannel<Object?> keyEvent = BasicMessageChannel<Object?>(
       'flutter/keyevent',
       JSONMessageCodec(),
   );
@@ -271,7 +271,7 @@ class SystemChannels {
   ///    applications to release caches to free up more memory. See
   ///    [WidgetsBindingObserver.didHaveMemoryPressure], which triggers whenever
   ///    a message is received on this channel.
-  static const BasicMessageChannel<dynamic> system = BasicMessageChannel<dynamic>(
+  static const BasicMessageChannel<Object?> system = BasicMessageChannel<Object?>(
       'flutter/system',
       JSONMessageCodec(),
   );
@@ -283,7 +283,7 @@ class SystemChannels {
   ///  * [SemanticsEvent] and its subclasses for a list of valid accessibility
   ///    events that can be sent over this channel.
   ///  * [SemanticsNode.sendEvent], which uses this channel to dispatch events.
-  static const BasicMessageChannel<dynamic> accessibility = BasicMessageChannel<dynamic>(
+  static const BasicMessageChannel<Object?> accessibility = BasicMessageChannel<Object?>(
     'flutter/accessibility',
     StandardMessageCodec(),
   );
@@ -311,7 +311,7 @@ class SystemChannels {
 
   /// A [MethodChannel] for configuring mouse cursors.
   ///
-  /// All outgoing methods defined for this channel uses a `Map<String, dynamic>`
+  /// All outgoing methods defined for this channel uses a `Map<String, Object?>`
   /// to contain multiple parameters, including the following methods (invoked
   /// using [OptionalMethodChannel.invokeMethod]):
   ///
diff --git a/packages/flutter/test/services/raw_keyboard_test.dart b/packages/flutter/test/services/raw_keyboard_test.dart
index 85544492cf..4a99fe4777 100644
--- a/packages/flutter/test/services/raw_keyboard_test.dart
+++ b/packages/flutter/test/services/raw_keyboard_test.dart
@@ -1086,15 +1086,15 @@ void main() {
         LogicalKeyboardKey.keyA,
         platform: 'android',
       );
-      Map<String, dynamic>? message;
+      Map<String, Object?>? message;
       await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {
-          message = SystemChannels.keyEvent.codec.decodeMessage(data) as Map<String, dynamic>;
+          message = SystemChannels.keyEvent.codec.decodeMessage(data) as Map<String, Object?>?;
         },
       );
-      expect(message, equals(<String, dynamic>{ 'handled': false }));
+      expect(message, equals(<String, Object?>{ 'handled': false }));
       message = null;
 
       // Set up a widget that will receive focused text events.
@@ -1115,15 +1115,15 @@ void main() {
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {
-          message = SystemChannels.keyEvent.codec.decodeMessage(data) as Map<String, dynamic>;
+          message = SystemChannels.keyEvent.codec.decodeMessage(data) as Map<String, Object?>?;
         },
       );
-      expect(message, equals(<String, dynamic>{ 'handled': true }));
+      expect(message, equals(<String, Object?>{ 'handled': true }));
       tester.binding.defaultBinaryMessenger.setMockMessageHandler(SystemChannels.keyEvent.name, null);
     });
 
     test('data.toString', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'android',
         'keyCode': 29,
@@ -1141,7 +1141,7 @@ void main() {
     });
 
     test('data.equality', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'android',
         'keyCode': 29,
@@ -1833,7 +1833,7 @@ void main() {
     });
 
     test('Unprintable keyboard keys are correctly translated', () {
-      final RawKeyEvent leftArrowKey = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent leftArrowKey = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'windows',
         'keyCode': 37, // keyCode for left arrow.
@@ -1854,7 +1854,7 @@ void main() {
       Future<void> simulateKeyEventMessage(String type, int keyCode, int scanCode) {
         return ServicesBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
           SystemChannels.keyEvent.name,
-          SystemChannels.keyEvent.codec.encodeMessage(<String, dynamic>{
+          SystemChannels.keyEvent.codec.encodeMessage(<String, Object?>{
             'type': type,
             'keymap': platform,
             'keyCode': keyCode,
@@ -1862,8 +1862,8 @@ void main() {
             'modifiers': 0,
           }),
           (ByteData? data) {
-            final Map<String, dynamic> decoded = SystemChannels.keyEvent.codec.decodeMessage(data) as Map<String, dynamic>;
-            lastHandled = decoded['handled'] as bool;
+            final Map<String, Object?> decoded = SystemChannels.keyEvent.codec.decodeMessage(data)! as Map<String, Object?>;
+            lastHandled = decoded['handled']! as bool;
           },
         );
       }
@@ -1879,7 +1879,7 @@ void main() {
     });
 
     test('data.toString', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'windows',
         'keyCode': 0x00000010,
@@ -1891,7 +1891,7 @@ void main() {
     });
 
     test('data.equality', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'windows',
         'keyCode': 0x00000010,
@@ -1905,7 +1905,7 @@ void main() {
         characterCodePoint: 10,
       ));
 
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'windows',
         'keyCode': 0x00000010,
@@ -1950,7 +1950,7 @@ void main() {
       for (final int modifier in modifierTests.keys) {
         for (final bool isDown in <bool>[true, false]) {
           for (final bool isLeft in <bool>[true, false]) {
-            final RawKeyEvent event = RawKeyEvent.fromMessage(<String, dynamic>{
+            final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
               'type': isDown ? 'keydown' : 'keyup',
               'keymap': 'linux',
               'toolkit': 'glfw',
@@ -1988,7 +1988,7 @@ void main() {
           // No need to combine CTRL key with itself.
           continue;
         }
-        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, dynamic>{
+        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
           'type': 'keydown',
           'keymap': 'linux',
           'toolkit': 'glfw',
@@ -2024,7 +2024,7 @@ void main() {
     });
 
     test('Printable keyboard keys are correctly translated', () {
-      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2040,7 +2040,7 @@ void main() {
     });
 
     test('Code points with two Unicode scalar values are allowed', () {
-      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2058,7 +2058,7 @@ void main() {
     test('Code points with more than three Unicode scalar values are not allowed', () {
       // |keyCode| and |scanCode| are arbitrary values. This test should fail due to an invalid |unicodeScalarValues|.
       void _createFailingKey() {
-        RawKeyEvent.fromMessage(const <String, dynamic>{
+        RawKeyEvent.fromMessage(const <String, Object?>{
           'type': 'keydown',
           'keymap': 'linux',
           'toolkit': 'glfw',
@@ -2073,7 +2073,7 @@ void main() {
     });
 
     test('Control keyboard keys are correctly translated', () {
-      final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2089,7 +2089,7 @@ void main() {
     });
 
     test('Modifier keyboard keys are correctly translated', () {
-      final RawKeyEvent shiftLeftKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent shiftLeftKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2104,7 +2104,7 @@ void main() {
     });
 
     test('data.toString', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2117,7 +2117,7 @@ void main() {
     });
 
     test('data.equality', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2134,7 +2134,7 @@ void main() {
         isDown: true,
       ));
 
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'glfw',
@@ -2182,7 +2182,7 @@ void main() {
       for (final int modifier in modifierTests.keys) {
         for (final bool isDown in <bool>[true, false]) {
           for (final bool isLeft in <bool>[true, false]) {
-            final RawKeyEvent event = RawKeyEvent.fromMessage(<String, dynamic>{
+            final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
               'type': isDown ? 'keydown' : 'keyup',
               'keymap': 'linux',
               'toolkit': 'gtk',
@@ -2220,7 +2220,7 @@ void main() {
           // No need to combine CTRL key with itself.
           continue;
         }
-        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, dynamic>{
+        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
           'type': 'keydown',
           'keymap': 'linux',
           'toolkit': 'gtk',
@@ -2256,7 +2256,7 @@ void main() {
     });
 
     test('Printable keyboard keys are correctly translated', () {
-      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2272,7 +2272,7 @@ void main() {
     });
 
     test('Code points with two Unicode scalar values are allowed', () {
-      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2290,7 +2290,7 @@ void main() {
     test('Code points with more than three Unicode scalar values are not allowed', () {
       // |keyCode| and |scanCode| are arbitrary values. This test should fail due to an invalid |unicodeScalarValues|.
       void _createFailingKey() {
-        RawKeyEvent.fromMessage(const <String, dynamic>{
+        RawKeyEvent.fromMessage(const <String, Object?>{
           'type': 'keydown',
           'keymap': 'linux',
           'toolkit': 'gtk',
@@ -2305,7 +2305,7 @@ void main() {
     });
 
     test('Control keyboard keys are correctly translated', () {
-      final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2321,7 +2321,7 @@ void main() {
     });
 
     test('Modifier keyboard keys are correctly translated', () {
-      final RawKeyEvent shiftLeftKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent shiftLeftKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2336,7 +2336,7 @@ void main() {
     });
 
     test('data.toString', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2349,7 +2349,7 @@ void main() {
     });
 
     test('data.equality', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2366,7 +2366,7 @@ void main() {
         isDown: true,
       ));
 
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2383,7 +2383,7 @@ void main() {
         isDown: true,
       ))));
 
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'linux',
         'toolkit': 'gtk',
@@ -2410,7 +2410,7 @@ void main() {
 
     test('modifier keys are recognized individually', () {
       for (final int modifier in modifierTests.keys) {
-        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, dynamic>{
+        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
           'type': 'keydown',
           'keymap': 'web',
           'code': 'RandomCode',
@@ -2441,7 +2441,7 @@ void main() {
           // No need to combine meta key with itself.
           continue;
         }
-        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, dynamic>{
+        final RawKeyEvent event = RawKeyEvent.fromMessage(<String, Object?>{
           'type': 'keydown',
           'keymap': 'web',
           'code': 'RandomCode',
@@ -2469,7 +2469,7 @@ void main() {
     });
 
     test('Printable keyboard keys are correctly translated', () {
-      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent keyAEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'KeyA',
@@ -2484,7 +2484,7 @@ void main() {
     });
 
     test('Control keyboard keys are correctly translated', () {
-      final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent escapeKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'Escape',
@@ -2499,7 +2499,7 @@ void main() {
     });
 
     test('Modifier keyboard keys are correctly translated', () {
-      final RawKeyEvent shiftKeyEvent = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent shiftKeyEvent = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'ShiftLeft',
@@ -2514,7 +2514,7 @@ void main() {
     });
 
     test('Arrow keys from a keyboard give correct physical key mappings', () {
-      final RawKeyEvent arrowKeyDown = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent arrowKeyDown = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'ArrowDown',
@@ -2529,7 +2529,7 @@ void main() {
     });
 
     test('Unrecognized keys are mapped to Web plane', () {
-      final RawKeyEvent arrowKeyDown = RawKeyEvent.fromMessage(const <String, dynamic>{
+      final RawKeyEvent arrowKeyDown = RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'Unrecog1',
@@ -2548,7 +2548,7 @@ void main() {
     });
 
     test('data.toString', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'KeyA',
@@ -2559,7 +2559,7 @@ void main() {
         'RawKeyEventDataWeb#00000(code: KeyA, key: a, location: 2, metaState: 16)'));
 
       // Without location
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'KeyA',
@@ -2570,7 +2570,7 @@ void main() {
     });
 
     test('data.equality', () {
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'KeyA',
@@ -2584,7 +2584,7 @@ void main() {
         metaState: 0x10,
       ));
 
-      expect(RawKeyEvent.fromMessage(const <String, dynamic>{
+      expect(RawKeyEvent.fromMessage(const <String, Object?>{
         'type': 'keydown',
         'keymap': 'web',
         'code': 'KeyA',
@@ -2610,6 +2610,6 @@ Future<void> _runWhileOverridingOnError(AsyncCallback body, {required FlutterExc
 Map<String, DiagnosticsNode> _groupDiagnosticsByName(Iterable<DiagnosticsNode> infos) {
   return Map<String, DiagnosticsNode>.fromIterable(
     infos,
-    key: (dynamic node) => (node as DiagnosticsNode).name ?? '',
+    key: (Object? node) => (node! as DiagnosticsNode).name ?? '',
   );
 }
diff --git a/packages/flutter_test/lib/src/event_simulation.dart b/packages/flutter_test/lib/src/event_simulation.dart
index 07eac0b9a9..ff91e995f9 100644
--- a/packages/flutter_test/lib/src/event_simulation.dart
+++ b/packages/flutter_test/lib/src/event_simulation.dart
@@ -688,8 +688,8 @@ class KeyEventSimulator {
             result.complete(false);
             return;
           }
-          final Map<String, dynamic> decoded = SystemChannels.keyEvent.codec.decodeMessage(data) as Map<String, dynamic>;
-          result.complete(decoded['handled'] as bool);
+          final Map<String, Object?> decoded = SystemChannels.keyEvent.codec.decodeMessage(data)! as Map<String, dynamic>;
+          result.complete(decoded['handled']! as bool);
         }
       );
       return result.future;