diff --git a/packages/smooth_app/lib/helpers/user_management_helper.dart b/packages/smooth_app/lib/helpers/user_management_helper.dart
index c95aee58618..3c3f44cb8f9 100644
--- a/packages/smooth_app/lib/helpers/user_management_helper.dart
+++ b/packages/smooth_app/lib/helpers/user_management_helper.dart
@@ -20,6 +20,9 @@ class UserManagementHelper {
   static bool isUsernameValid(final String username) =>
       username.isNotEmpty && _userRegex.hasMatch(username);
 
+  static bool isUsernameLengthValid(final String username) =>
+      username.length <= 20;
+
   static bool isPasswordValid(final String password) => password.length >= 6;
 }
 
diff --git a/packages/smooth_app/lib/pages/user_management/sign_up_page.dart b/packages/smooth_app/lib/pages/user_management/sign_up_page.dart
index 681a4e68dc3..b295c059bd2 100644
--- a/packages/smooth_app/lib/pages/user_management/sign_up_page.dart
+++ b/packages/smooth_app/lib/pages/user_management/sign_up_page.dart
@@ -117,6 +117,10 @@ class _SignUpPageState extends State<SignUpPage> {
                     _userController.trimmedText)) {
                   return appLocalizations.sign_up_page_username_description;
                 }
+                if (!UserManagementHelper.isUsernameLengthValid(
+                    _userController.trimmedText)) {
+                  return 'Username must be less than 20 characters'; // TODO(vik4114): localization
+                }
                 return null;
               },
             ),