diff --git a/shell/platform/fuchsia/dart_runner/dart_component_controller.cc b/shell/platform/fuchsia/dart_runner/dart_component_controller.cc
index c86ff1208cd85..666a29cba63a8 100644
--- a/shell/platform/fuchsia/dart_runner/dart_component_controller.cc
+++ b/shell/platform/fuchsia/dart_runner/dart_component_controller.cc
@@ -310,8 +310,6 @@ bool DartComponentController::SetUpFromKernel() {
                   manifest.size());
   Dart_Handle library = Dart_Null();
 
-  bool first_library = true;
-  bool result_sound_null_safety = false;
   for (size_t start = 0; start < manifest.size();) {
     size_t end = str.find("\n", start);
     if (end == std::string::npos) {
@@ -330,31 +328,11 @@ bool DartComponentController::SetUpFromKernel() {
       Dart_ExitScope();
       return false;
     }
-    bool sound_null_safety = Dart_DetectNullSafety(
-        /*script_uri=*/nullptr, /*package_config=*/nullptr,
-        /*original_working_directory=*/nullptr,
-        isolate_snapshot_data_.address(),
-        /*isolate_snapshot_instructions=*/nullptr, kernel.address(),
-        kernel.size());
-
-    if (first_library) {
-      result_sound_null_safety = sound_null_safety;
-      first_library = false;
-    } else if (sound_null_safety != result_sound_null_safety) {
-      FML_LOG(ERROR) << "Inconsistent sound null safety";
-      return false;
-    }
-
     kernel_peices_.emplace_back(std::move(kernel));
   }
 
-  Dart_IsolateFlags isolate_flags;
-  Dart_IsolateFlagsInitialize(&isolate_flags);
-  isolate_flags.null_safety = result_sound_null_safety;
-
   if (!CreateIsolate(isolate_snapshot_data_.address(),
-                     /*isolate_snapshot_instructions=*/nullptr,
-                     &isolate_flags)) {
+                     /*isolate_snapshot_instructions=*/nullptr)) {
     return false;
   }
 
@@ -404,15 +382,13 @@ bool DartComponentController::SetUpFromAppSnapshot() {
     isolate_data = isolate_snapshot_data_.address();
     isolate_instructions = nullptr;
   }
-  return CreateIsolate(isolate_data, isolate_instructions,
-                       /*isolate_flags=*/nullptr);
+  return CreateIsolate(isolate_data, isolate_instructions);
 #endif  // defined(AOT_RUNTIME)
 }
 
 bool DartComponentController::CreateIsolate(
     const uint8_t* isolate_snapshot_data,
-    const uint8_t* isolate_snapshot_instructions,
-    Dart_IsolateFlags* isolate_flags) {
+    const uint8_t* isolate_snapshot_instructions) {
   // Create the isolate from the snapshot.
   char* error = nullptr;
 
@@ -423,9 +399,13 @@ bool DartComponentController::CreateIsolate(
   auto state = new std::shared_ptr<tonic::DartState>(new tonic::DartState(
       namespace_fd, [this](Dart_Handle result) { MessageEpilogue(result); }));
 
+  Dart_IsolateFlags isolate_flags;
+  Dart_IsolateFlagsInitialize(&isolate_flags);
+  isolate_flags.null_safety = true;
+
   isolate_ = Dart_CreateIsolateGroup(
       url_.c_str(), label_.c_str(), isolate_snapshot_data,
-      isolate_snapshot_instructions, isolate_flags, state, state, &error);
+      isolate_snapshot_instructions, &isolate_flags, state, state, &error);
   if (!isolate_) {
     FML_LOG(ERROR) << "Dart_CreateIsolateGroup failed: " << error;
     return false;
diff --git a/shell/platform/fuchsia/dart_runner/dart_component_controller.h b/shell/platform/fuchsia/dart_runner/dart_component_controller.h
index e8c3701a22458..fdc244079217a 100644
--- a/shell/platform/fuchsia/dart_runner/dart_component_controller.h
+++ b/shell/platform/fuchsia/dart_runner/dart_component_controller.h
@@ -61,8 +61,7 @@ class DartComponentController
   bool SetUpFromAppSnapshot();
 
   bool CreateIsolate(const uint8_t* isolate_snapshot_data,
-                     const uint8_t* isolate_snapshot_instructions,
-                     Dart_IsolateFlags* isolate_flags);
+                     const uint8_t* isolate_snapshot_instructions);
 
   // |Echo|
   void EchoString(fidl::StringPtr value, EchoStringCallback callback) override;
diff --git a/shell/platform/fuchsia/dart_runner/dart_test_component_controller.cc b/shell/platform/fuchsia/dart_runner/dart_test_component_controller.cc
index d7c6b311820fe..d9d4b07120e2d 100644
--- a/shell/platform/fuchsia/dart_runner/dart_test_component_controller.cc
+++ b/shell/platform/fuchsia/dart_runner/dart_test_component_controller.cc
@@ -242,8 +242,6 @@ bool DartTestComponentController::SetUpFromKernel() {
                   manifest.size());
   Dart_Handle library = Dart_Null();
 
-  bool first_library = true;
-  bool result_sound_null_safety = false;
   for (size_t start = 0; start < manifest.size();) {
     size_t end = str.find("\n", start);
     if (end == std::string::npos) {
@@ -260,31 +258,11 @@ bool DartTestComponentController::SetUpFromKernel() {
       FML_LOG(ERROR) << "Cannot load kernel from namespace: " << path;
       return false;
     }
-    bool sound_null_safety = Dart_DetectNullSafety(
-        /*script_uri=*/nullptr, /*package_config=*/nullptr,
-        /*original_working_directory=*/nullptr,
-        isolate_snapshot_data_.address(),
-        /*isolate_snapshot_instructions=*/nullptr, kernel.address(),
-        kernel.size());
-
-    if (first_library) {
-      result_sound_null_safety = sound_null_safety;
-      first_library = false;
-    } else if (sound_null_safety != result_sound_null_safety) {
-      FML_LOG(ERROR) << "Inconsistent sound null safety";
-      return false;
-    }
-
     kernel_peices_.emplace_back(std::move(kernel));
   }
 
-  Dart_IsolateFlags isolate_flags;
-  Dart_IsolateFlagsInitialize(&isolate_flags);
-  isolate_flags.null_safety = result_sound_null_safety;
-
   if (!CreateIsolate(isolate_snapshot_data_.address(),
-                     /*isolate_snapshot_instructions=*/nullptr,
-                     &isolate_flags)) {
+                     /*isolate_snapshot_instructions=*/nullptr)) {
     return false;
   }
 
@@ -333,15 +311,13 @@ bool DartTestComponentController::SetUpFromAppSnapshot() {
     isolate_data = isolate_snapshot_data_.address();
     isolate_instructions = nullptr;
   }
-  return CreateIsolate(isolate_data, isolate_instructions,
-                       /*isolate_flags=*/nullptr);
+  return CreateIsolate(isolate_data, isolate_instructions);
 #endif  // defined(AOT_RUNTIME)
 }
 
 bool DartTestComponentController::CreateIsolate(
     const uint8_t* isolate_snapshot_data,
-    const uint8_t* isolate_snapshot_instructions,
-    Dart_IsolateFlags* isolate_flags) {
+    const uint8_t* isolate_snapshot_instructions) {
   // Create the isolate from the snapshot.
   char* error = nullptr;
 
@@ -352,9 +328,13 @@ bool DartTestComponentController::CreateIsolate(
   auto state = new std::shared_ptr<tonic::DartState>(new tonic::DartState(
       namespace_fd, [this](Dart_Handle result) { MessageEpilogue(result); }));
 
+  Dart_IsolateFlags isolate_flags;
+  Dart_IsolateFlagsInitialize(&isolate_flags);
+  isolate_flags.null_safety = true;
+
   isolate_ = Dart_CreateIsolateGroup(
       url_.c_str(), label_.c_str(), isolate_snapshot_data,
-      isolate_snapshot_instructions, isolate_flags, state, state, &error);
+      isolate_snapshot_instructions, &isolate_flags, state, state, &error);
   if (!isolate_) {
     FML_LOG(ERROR) << "Dart_CreateIsolateGroup failed: " << error;
     return false;
diff --git a/shell/platform/fuchsia/dart_runner/dart_test_component_controller.h b/shell/platform/fuchsia/dart_runner/dart_test_component_controller.h
index 3bf9437f2ef52..81655653342d4 100644
--- a/shell/platform/fuchsia/dart_runner/dart_test_component_controller.h
+++ b/shell/platform/fuchsia/dart_runner/dart_test_component_controller.h
@@ -77,8 +77,7 @@ class DartTestComponentController
   bool SetUpFromAppSnapshot();
 
   bool CreateIsolate(const uint8_t* isolate_snapshot_data,
-                     const uint8_t* isolate_snapshot_instructions,
-                     Dart_IsolateFlags* isolate_flags);
+                     const uint8_t* isolate_snapshot_instructions);
 
   // |ComponentController|
   void Kill() override;
diff --git a/shell/platform/fuchsia/dart_runner/service_isolate.cc b/shell/platform/fuchsia/dart_runner/service_isolate.cc
index c9af7409a8398..59d9cb8fbf999 100644
--- a/shell/platform/fuchsia/dart_runner/service_isolate.cc
+++ b/shell/platform/fuchsia/dart_runner/service_isolate.cc
@@ -122,19 +122,9 @@ Dart_Isolate CreateServiceIsolate(
   }
 #endif
 
-  bool is_null_safe =
-      Dart_DetectNullSafety(nullptr,         // script_uri
-                            nullptr,         // package_config
-                            nullptr,         // original_working_directory
-                            vmservice_data,  // snapshot_data
-                            vmservice_instructions,  // snapshot_instructions
-                            nullptr,                 // kernel_buffer
-                            0u                       // kernel_buffer_size
-      );
-
   Dart_IsolateFlags flags;
   Dart_IsolateFlagsInitialize(&flags);
-  flags.null_safety = is_null_safe;
+  flags.null_safety = true;
 
   auto state = new std::shared_ptr<tonic::DartState>(new tonic::DartState());
   Dart_Isolate isolate = Dart_CreateIsolateGroup(
diff --git a/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_echo_server/BUILD.gn b/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_echo_server/BUILD.gn
index 100b1d04ff724..87db0a6fcb46f 100644
--- a/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_echo_server/BUILD.gn
+++ b/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_echo_server/BUILD.gn
@@ -11,7 +11,6 @@ import("//flutter/tools/fuchsia/gn-sdk/src/package.gni")
 dart_library("lib") {
   testonly = true
   package_name = "dart_echo_server"
-  null_safe = true
 
   source_dir = "."
   sources = [ "main.dart" ]
@@ -20,7 +19,6 @@ dart_library("lib") {
 # Dart component that serves the test Echo FIDL protocol, built using the Dart AOT runner
 dart_component("aot_component") {
   testonly = true
-  null_safe = true
 
   main_package = "dart_echo_server"
   manifest = "meta/dart-aot-echo-server.cml"
@@ -32,7 +30,6 @@ dart_component("aot_component") {
 # Dart component that serves the test Echo FIDL protocol, built using the Dart AOT runner
 dart_component("jit_component") {
   testonly = true
-  null_safe = true
 
   main_package = "dart_echo_server"
   manifest = "meta/dart-jit-echo-server.cml"
diff --git a/shell/platform/fuchsia/flutter/tests/integration/embedder/parent-view/lib/parent_view.dart b/shell/platform/fuchsia/flutter/tests/integration/embedder/parent-view/lib/parent_view.dart
index 8cb272e34d91b..918bef8260b54 100644
--- a/shell/platform/fuchsia/flutter/tests/integration/embedder/parent-view/lib/parent_view.dart
+++ b/shell/platform/fuchsia/flutter/tests/integration/embedder/parent-view/lib/parent_view.dart
@@ -50,7 +50,7 @@ class TestApp {
       this.focusable = true}) {}
 
   void run() {
-    childView.create(focusable, (ByteData reply) {
+    childView.create(focusable, (ByteData? reply) {
       // Set up window allbacks.
       window.onPointerDataPacket = (PointerDataPacket packet) {
         for (final data in packet.data) {
@@ -181,8 +181,8 @@ Future<int> _launchChildView() async {
   final message = Int8List.fromList([0x31]);
   final completer = new Completer<ByteData>();
   PlatformDispatcher.instance.sendPlatformMessage(
-      'fuchsia/child_view', ByteData.sublistView(message), (ByteData reply) {
-    completer.complete(reply);
+      'fuchsia/child_view', ByteData.sublistView(message), (ByteData? reply) {
+    completer.complete(reply!);
   });
 
   return int.parse(
diff --git a/shell/platform/fuchsia/flutter/tests/integration/mouse-input/mouse-input-view/lib/mouse-input-view.dart b/shell/platform/fuchsia/flutter/tests/integration/mouse-input/mouse-input-view/lib/mouse-input-view.dart
index 9e990890ee6af..b3f2104c5747c 100644
--- a/shell/platform/fuchsia/flutter/tests/integration/mouse-input/mouse-input-view/lib/mouse-input-view.dart
+++ b/shell/platform/fuchsia/flutter/tests/integration/mouse-input/mouse-input-view/lib/mouse-input-view.dart
@@ -100,13 +100,13 @@ class MyApp {
   }
 
   void _reportMouseInput(
-      {double localX,
-      double localY,
-      int timeReceived,
-      int buttons,
-      String phase,
-      double wheelXPhysicalPixel,
-      double wheelYPhysicalPixel}) {
+      {required double localX,
+      required double localY,
+      required int timeReceived,
+      required int buttons,
+      required String phase,
+      required double wheelXPhysicalPixel,
+      required double wheelYPhysicalPixel}) {
     print('mouse-input-view reporting mouse input to MouseInputListener');
     final message = ByteData.sublistView(utf8.encode(json.encode({
         'method': 'MouseInputListener.ReportMouseInput',
@@ -115,7 +115,7 @@ class MyApp {
         'time_received': timeReceived,
         'component_name': 'touch-input-view',
         'buttons': buttons,
-        'phase': 'asdf',
+        'phase': phase,
         'wheel_x_physical_pixel': wheelXPhysicalPixel,
         'wheel_y_physical_pixel': wheelYPhysicalPixel,
       })));
diff --git a/shell/platform/fuchsia/flutter/tests/integration/text-input/text-input-view/BUILD.gn b/shell/platform/fuchsia/flutter/tests/integration/text-input/text-input-view/BUILD.gn
index 38d8760bdbd9a..c2c289ce22a73 100644
--- a/shell/platform/fuchsia/flutter/tests/integration/text-input/text-input-view/BUILD.gn
+++ b/shell/platform/fuchsia/flutter/tests/integration/text-input/text-input-view/BUILD.gn
@@ -13,7 +13,6 @@ dart_library("lib") {
   package_name = "text-input-view"
   sources = [ "text_input_view.dart" ]
   deps = [ "//flutter/shell/platform/fuchsia/dart:args" ]
-  null_safe = true
 }
 
 flutter_component("component") {
@@ -22,7 +21,6 @@ flutter_component("component") {
   manifest = rebase_path("meta/text-input-view.cml")
   main_package = "text-input-view"
   main_dart = "text_input_view.dart"
-  sound_null_safety = true
   deps = [ ":lib" ]
 }
 
diff --git a/shell/platform/fuchsia/flutter/tests/integration/touch-input/embedding-flutter-view/lib/embedding-flutter-view.dart b/shell/platform/fuchsia/flutter/tests/integration/touch-input/embedding-flutter-view/lib/embedding-flutter-view.dart
index 4f3613427818b..39a161a05ee44 100644
--- a/shell/platform/fuchsia/flutter/tests/integration/touch-input/embedding-flutter-view/lib/embedding-flutter-view.dart
+++ b/shell/platform/fuchsia/flutter/tests/integration/touch-input/embedding-flutter-view/lib/embedding-flutter-view.dart
@@ -53,7 +53,7 @@ class TestApp {
   }
 
   void run() {
-    childView.create(focusable, (ByteData reply) {
+    childView.create(focusable, (ByteData? reply) {
         // Set up window callbacks.
         window.onPointerDataPacket = (PointerDataPacket packet) {
           this.pointerDataPacket(packet);
@@ -161,7 +161,7 @@ class TestApp {
     window.scheduleFrame();
   }
 
-  void _reportTouchInput({double localX, double localY, int timeReceived}) {
+  void _reportTouchInput({required double localX, required double localY, required int timeReceived}) {
     print('embedding-flutter-view reporting touch input to TouchInputListener');
     final message = utf8.encode(json.encode({
       'method': 'TouchInputListener.ReportTouchInput',
@@ -219,8 +219,8 @@ Future<int> _launchChildView() async {
   final message = Int8List.fromList([0x31]);
   final completer = new Completer<ByteData>();
   PlatformDispatcher.instance.sendPlatformMessage(
-      'fuchsia/child_view', ByteData.sublistView(message), (ByteData reply) {
-    completer.complete(reply);
+      'fuchsia/child_view', ByteData.sublistView(message), (ByteData? reply) {
+    completer.complete(reply!);
   });
 
   return int.parse(
diff --git a/shell/platform/fuchsia/flutter/tests/integration/touch-input/touch-input-view/lib/touch-input-view.dart b/shell/platform/fuchsia/flutter/tests/integration/touch-input/touch-input-view/lib/touch-input-view.dart
index b8cb1c98c985a..8032b1e4ba20b 100644
--- a/shell/platform/fuchsia/flutter/tests/integration/touch-input/touch-input-view/lib/touch-input-view.dart
+++ b/shell/platform/fuchsia/flutter/tests/integration/touch-input/touch-input-view/lib/touch-input-view.dart
@@ -80,7 +80,7 @@ class TestApp {
     window.scheduleFrame();
   }
 
-  void _reportTouchInput({double localX, double localY, int timeReceived}) {
+  void _reportTouchInput({required double localX, required double localY, required int timeReceived}) {
     print('touch-input-view reporting touch input to TouchInputListener');
     final message = utf8.encode(json.encode({
       'method': 'TouchInputListener.ReportTouchInput',
diff --git a/tools/fuchsia/dart/dart_component.gni b/tools/fuchsia/dart/dart_component.gni
index 7e76ebf80e349..8cf19ba8a3f87 100644
--- a/tools/fuchsia/dart/dart_component.gni
+++ b/tools/fuchsia/dart/dart_component.gni
@@ -81,9 +81,6 @@ import("//flutter/tools/fuchsia/flutter/internal/flutter_dart_component.gni")
 #     Specifies the parameters for building the component.
 #     See //build/dart/dart_build_config.gni for predefined configs.
 #
-#   null_safe (optional)
-#    If true, this component will be compiled with --sound-null-safety
-#
 #  deps
 #  testonly
 #  visibility
@@ -123,7 +120,6 @@ template("dart_component") {
                              "build_cfg",
                              "deps",
                              "main_dart",
-                             "null_safe",
                            ])
     main_package = _main_package
     deps = _component_deps
diff --git a/tools/fuchsia/dart/dart_library.gni b/tools/fuchsia/dart/dart_library.gni
index 5eea0fe04e991..ed3ded2cc930f 100644
--- a/tools/fuchsia/dart/dart_library.gni
+++ b/tools/fuchsia/dart/dart_library.gni
@@ -76,9 +76,6 @@ import("//flutter/tools/fuchsia/dart/toolchain.gni")
 #   disable_metadata_entry (optional)
 #     Prevents metedata entry from being written to the dart_packag_config json file.
 #
-#   null_safe (optional)
-#     A flag that enables null safety check in dart libraries.
-#
 # Example of usage:
 #
 #   dart_library("baz") {
@@ -183,10 +180,10 @@ if (current_toolchain == dart_toolchain) {
           name = package_name
           if (defined(invoker.language_version)) {
             language_version = invoker.language_version
-          } else if (defined(invoker.null_safe) && invoker.null_safe) {
-            language_version = "2.12"
           } else if (defined(invoker.pubspec)) {
             pubspec_path = rebase_path(invoker.pubspec, root_build_dir)
+          } else {
+            language_version = "2.12"
           }
           root_uri = rebase_path(package_root, root_build_dir)
           if (defined(invoker.source_dir)) {
diff --git a/tools/fuchsia/dart/kernel/dart_kernel.gni b/tools/fuchsia/dart/kernel/dart_kernel.gni
index aa7c908cc50f6..6053eb5f1e504 100644
--- a/tools/fuchsia/dart/kernel/dart_kernel.gni
+++ b/tools/fuchsia/dart/kernel/dart_kernel.gni
@@ -135,9 +135,6 @@ template("_convert_kernel_manifest") {
 #    Whether the kernel compiler should link the current platform.dill into
 #    the build. If false, the --no-link-platform flag will be passed to the
 #    compiler. Defaults to false.
-#
-#  sound_null_safety (optional)
-#    Whether to generate sound null safe kernel.
 template("dart_kernel") {
   assert(defined(invoker.platform_name), "dart_kernel() requires platform_name")
   assert(defined(invoker.packages_path),
@@ -278,12 +275,9 @@ template("dart_kernel") {
       rebase_path(depfile, root_build_dir),
       "--output",
       rebase_path(_kernel_path, root_build_dir),
+      "--sound-null-safety",
     ]
 
-    if (!defined(invoker.sound_null_safety) || !invoker.sound_null_safety) {
-      args += [ "--no-sound-null-safety" ]
-    }
-
     # TODO(richkadel): It should be possible to remove all of the build rules
     # related to `generate_manifest`. Without the following two flags, the
     # `gen_kernel` step will produce one large `.dil` file, instead of multiple
diff --git a/tools/fuchsia/flutter/flutter_component.gni b/tools/fuchsia/flutter/flutter_component.gni
index 3932ddf354852..8fd99842cbba0 100644
--- a/tools/fuchsia/flutter/flutter_component.gni
+++ b/tools/fuchsia/flutter/flutter_component.gni
@@ -84,9 +84,6 @@ import("//flutter/tools/fuchsia/flutter/internal/flutter_dart_component.gni")
 #     Specifies the parameters for building the component.
 #     See //flutter/tools/fuchsia/flutter/flutter_build_config.gni for predefined configs.
 #
-#   sound_null_safety (optional)
-#     Whether to generate sound null safe Dart kernel.
-#
 #  deps
 #  testonly
 #  visibility
diff --git a/tools/fuchsia/flutter/internal/flutter_dart_component.gni b/tools/fuchsia/flutter/internal/flutter_dart_component.gni
index d43d6f753fbc8..72cd952b8418b 100644
--- a/tools/fuchsia/flutter/internal/flutter_dart_component.gni
+++ b/tools/fuchsia/flutter/internal/flutter_dart_component.gni
@@ -48,9 +48,6 @@ import("//flutter/tools/fuchsia/gn-sdk/src/component.gni")
 #     Type: boolean
 #     Default: false
 #
-#   sound_null_safety (optional)
-#     If true, generate sound null safe Dart kernel.
-#
 #  deps
 #  testonly
 #  visibility
@@ -147,7 +144,6 @@ template("flutter_dart_component") {
                              "visibility",
                              "main_dart",
                              "main_package",
-                             "sound_null_safety",
                            ])
 
     deps = [ ":$_dart_package_config_target_name" ]
diff --git a/tools/fuchsia/sdk/sdk_targets.gni b/tools/fuchsia/sdk/sdk_targets.gni
index 159ce98c2ce36..f0b5c8a6490e8 100644
--- a/tools/fuchsia/sdk/sdk_targets.gni
+++ b/tools/fuchsia/sdk/sdk_targets.gni
@@ -17,11 +17,7 @@ template("_fuchsia_dart_library") {
   _sources = []
   _deps = []
 
-  if (defined(meta.dart_library_null_safe) && meta.dart_library_null_safe) {
-    _dart_language_version = "2.12"
-  } else {
-    _dart_language_version = "2.0"
-  }
+  _dart_language_version = "2.12"
 
   foreach(source, meta.sources) {
     _sources += [ string_replace("$source", "${meta.root}/lib/", "") ]