diff --git a/packages/pigeon/CHANGELOG.md b/packages/pigeon/CHANGELOG.md
index e3375af58e6..570cc706229 100644
--- a/packages/pigeon/CHANGELOG.md
+++ b/packages/pigeon/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 25.5.0
+
+* [dart] Changes the default InstanceManager and its initialization to no longer make a message call
+  when used in a Flutter unit test.
+
 ## 25.4.0
 
 * [gobject] Adds type id constants in header files so that they can be used by the user.
diff --git a/packages/pigeon/lib/src/dart/dart_generator.dart b/packages/pigeon/lib/src/dart/dart_generator.dart
index 4ce527e292a..2dcb9b2efad 100644
--- a/packages/pigeon/lib/src/dart/dart_generator.dart
+++ b/packages/pigeon/lib/src/dart/dart_generator.dart
@@ -146,6 +146,9 @@ class DartGenerator extends StructuredGenerator<InternalDartOptions> {
     required String dartPackageName,
   }) {
     indent.writeln("import 'dart:async';");
+    if (root.containsProxyApi) {
+      indent.writeln("import 'dart:io' show Platform;");
+    }
     indent.writeln(
       "import 'dart:typed_data' show Float64List, Int32List, Int64List, Uint8List;",
     );
diff --git a/packages/pigeon/lib/src/dart/templates.dart b/packages/pigeon/lib/src/dart/templates.dart
index 78b8e20ef26..73fbf92035b 100644
--- a/packages/pigeon/lib/src/dart/templates.dart
+++ b/packages/pigeon/lib/src/dart/templates.dart
@@ -87,6 +87,9 @@ class $dartInstanceManagerClassName {
   late final void Function(int) onWeakReferenceRemoved;
 
   static $dartInstanceManagerClassName _initInstance() {
+    if (Platform.environment['FLUTTER_TEST'] == 'true') {
+      return $dartInstanceManagerClassName(onWeakReferenceRemoved: (_) {});
+    }
     WidgetsFlutterBinding.ensureInitialized();
     final $dartInstanceManagerApiClassName api = $dartInstanceManagerApiClassName();
     // Clears the native `$dartInstanceManagerClassName` on the initial use of the Dart one.
diff --git a/packages/pigeon/lib/src/generator_tools.dart b/packages/pigeon/lib/src/generator_tools.dart
index 19b38e36d2e..8528dd70df8 100644
--- a/packages/pigeon/lib/src/generator_tools.dart
+++ b/packages/pigeon/lib/src/generator_tools.dart
@@ -15,7 +15,7 @@ import 'generator.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '25.4.0';
+const String pigeonVersion = '25.5.0';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {
diff --git a/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/proxy_api_tests.gen.dart b/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/proxy_api_tests.gen.dart
index 559b4d12ee2..4f6b8593aed 100644
--- a/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/proxy_api_tests.gen.dart
+++ b/packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/proxy_api_tests.gen.dart
@@ -7,6 +7,7 @@
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import, no_leading_underscores_for_local_identifiers
 
 import 'dart:async';
+import 'dart:io' show Platform;
 import 'dart:typed_data' show Float64List, Int32List, Int64List, Uint8List;
 
 import 'package:flutter/foundation.dart'
@@ -126,6 +127,9 @@ class PigeonInstanceManager {
   late final void Function(int) onWeakReferenceRemoved;
 
   static PigeonInstanceManager _initInstance() {
+    if (Platform.environment['FLUTTER_TEST'] == 'true') {
+      return PigeonInstanceManager(onWeakReferenceRemoved: (_) {});
+    }
     WidgetsFlutterBinding.ensureInitialized();
     final _PigeonInternalInstanceManagerApi api =
         _PigeonInternalInstanceManagerApi();
diff --git a/packages/pigeon/platform_tests/shared_test_plugin_code/test/instance_manager_test.dart b/packages/pigeon/platform_tests/shared_test_plugin_code/test/instance_manager_test.dart
index 66f9d955202..2582ed27a02 100644
--- a/packages/pigeon/platform_tests/shared_test_plugin_code/test/instance_manager_test.dart
+++ b/packages/pigeon/platform_tests/shared_test_plugin_code/test/instance_manager_test.dart
@@ -167,7 +167,7 @@ void main() {
       instanceManager.addDartCreatedInstance(object);
 
       object = null;
-      await forceGC();
+      await forceGC(fullGcCycles: 2);
 
       expect(weakReferencedRemovedCalled, isTrue);
     });
@@ -188,10 +188,49 @@ void main() {
       instanceManager.addHostCreatedInstance(object, 0);
 
       object = null;
-      await forceGC();
+      await forceGC(fullGcCycles: 2);
 
       expect(weakReferencedRemovedCalled, isFalse);
     });
+
+    testWidgets(
+      'instantiating default InstanceManager does not make a message call',
+      (WidgetTester tester) async {
+        bool messageCallMade = false;
+        TestDefaultBinaryMessengerBinding
+            .instance.defaultBinaryMessenger.allMessagesHandler = (_, __, ___) {
+          messageCallMade = true;
+          return null;
+        };
+
+        // Initialize default InstanceManager
+        // ignore: unnecessary_statements
+        PigeonInstanceManager.instance;
+
+        expect(messageCallMade, isFalse);
+      },
+    );
+
+    testWidgets(
+      'default InstanceManager does not make message call when weak reference is removed',
+      (WidgetTester tester) async {
+        bool messageCallMade = false;
+        TestDefaultBinaryMessengerBinding
+            .instance.defaultBinaryMessenger.allMessagesHandler = (_, __, ___) {
+          messageCallMade = true;
+          return null;
+        };
+
+        final PigeonInstanceManager instanceManager =
+            PigeonInstanceManager.instance;
+
+        final int identifier =
+            instanceManager.addDartCreatedInstance(CopyableObject());
+        instanceManager.onWeakReferenceRemoved(identifier);
+
+        expect(messageCallMade, isFalse);
+      },
+    );
   });
 }
 
diff --git a/packages/pigeon/pubspec.yaml b/packages/pigeon/pubspec.yaml
index bcc34f39bec..fc25e430e75 100644
--- a/packages/pigeon/pubspec.yaml
+++ b/packages/pigeon/pubspec.yaml
@@ -2,7 +2,7 @@ name: pigeon
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 repository: https://github.com/flutter/packages/tree/main/packages/pigeon
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+pigeon%22
-version: 25.4.0 # This must match the version in lib/src/generator_tools.dart
+version: 25.5.0 # This must match the version in lib/src/generator_tools.dart
 
 environment:
   sdk: ^3.6.0