diff --git a/packages/flutter/lib/src/material/app.dart b/packages/flutter/lib/src/material/app.dart
index 4a80123f79d..3b871d56a26 100644
--- a/packages/flutter/lib/src/material/app.dart
+++ b/packages/flutter/lib/src/material/app.dart
@@ -986,6 +986,16 @@ class _MaterialAppState extends State<MaterialApp> {
         },
       );
     }
+
+    childWidget = ScaffoldMessenger(
+      key: widget.scaffoldMessengerKey,
+      child: DefaultSelectionStyle(
+        selectionColor: effectiveSelectionColor,
+        cursorColor: effectiveCursorColor,
+        child: childWidget,
+      ),
+    );
+
     if (widget.themeAnimationStyle != AnimationStyle.noAnimation) {
       childWidget = AnimatedTheme(
         data: theme,
@@ -1000,14 +1010,7 @@ class _MaterialAppState extends State<MaterialApp> {
       );
     }
 
-    return ScaffoldMessenger(
-      key: widget.scaffoldMessengerKey,
-      child: DefaultSelectionStyle(
-        selectionColor: effectiveSelectionColor,
-        cursorColor: effectiveCursorColor,
-        child: childWidget,
-      ),
-    );
+    return childWidget;
   }
 
   Widget _buildWidgetApp(BuildContext context) {
diff --git a/packages/flutter/test/material/scaffold_test.dart b/packages/flutter/test/material/scaffold_test.dart
index c0cf2cd5e1e..a3efc1cec34 100644
--- a/packages/flutter/test/material/scaffold_test.dart
+++ b/packages/flutter/test/material/scaffold_test.dart
@@ -2867,7 +2867,30 @@ void main() {
       expect(tester.takeException(), isNull);
   });
 
-   testWidgets('ScaffoldMessenger showSnackBar default animation', (WidgetTester tester) async {
+  // Regression test for https://github.com/flutter/flutter/issues/115924.
+  testWidgets('Default ScaffoldMessenger can access ambient theme', (WidgetTester tester) async {
+    final GlobalKey<ScaffoldMessengerState> scaffoldMessengerKey = GlobalKey<ScaffoldMessengerState>();
+
+    final ColorScheme colorScheme = ColorScheme.fromSeed(seedColor: Colors.deepPurple);
+    final ThemeData customTheme = ThemeData(
+      colorScheme: colorScheme,
+      visualDensity: VisualDensity.comfortable,
+    );
+
+    await tester.pumpWidget(
+      MaterialApp(
+        scaffoldMessengerKey: scaffoldMessengerKey,
+        theme: customTheme,
+        home: const SizedBox.shrink(),
+      ),
+    );
+
+    final ThemeData messengerTheme = Theme.of(scaffoldMessengerKey.currentContext!);
+    expect(messengerTheme.colorScheme, colorScheme);
+    expect(messengerTheme.visualDensity, VisualDensity.comfortable);
+  });
+
+  testWidgets('ScaffoldMessenger showSnackBar default animation', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(
         body: Builder(