diff --git a/lib/flutter_timezone_web.dart b/lib/flutter_timezone_web.dart
index a57d8a0..a3500ba 100644
--- a/lib/flutter_timezone_web.dart
+++ b/lib/flutter_timezone_web.dart
@@ -24,7 +24,7 @@ class FlutterTimezonePlugin {
       case 'getLocalTimezone':
         return _getLocalTimeZone();
       case 'getAvailableTimezones':
-        return [_getLocalTimeZone()];
+        return _getAvailableTimezones();
       default:
         throw PlatformException(
             code: 'Unimplemented',
@@ -40,8 +40,18 @@ class FlutterTimezonePlugin {
   String _getLocalTimeZone() {
     return jsDateTimeFormat().resolvedOptions().timeZone;
   }
+
+  List<String> _getAvailableTimezones() {
+    final function = supportedValuesOf as _DartFunctionSupportedValuesOf?;
+    return function?.call('timeZone') ?? [_getLocalTimeZone()];
+  }
 }
 
+typedef _DartFunctionSupportedValuesOf = List<String> Function(String value);
+
+@JS('Intl.supportedValuesOf')
+external JSFunction? supportedValuesOf;
+
 @JS('Intl.DateTimeFormat')
 external _JSDateTimeFormat jsDateTimeFormat();