diff --git a/src/Aspire.Dashboard/Components/App.razor b/src/Aspire.Dashboard/Components/App.razor
index e9b3ca1f19e..b3ae5d33d89 100644
--- a/src/Aspire.Dashboard/Components/App.razor
+++ b/src/Aspire.Dashboard/Components/App.razor
@@ -1,5 +1,5 @@
 ﻿<!DOCTYPE html>
-<html lang="en">
+<html lang="@System.Globalization.CultureInfo.CurrentUICulture.Name">
 
 <head>
     <meta charset="utf-8" />
diff --git a/src/Aspire.Dashboard/Components/Dialogs/SettingsDialog.razor b/src/Aspire.Dashboard/Components/Dialogs/SettingsDialog.razor
index cd7891c5423..957960d3557 100644
--- a/src/Aspire.Dashboard/Components/Dialogs/SettingsDialog.razor
+++ b/src/Aspire.Dashboard/Components/Dialogs/SettingsDialog.razor
@@ -19,10 +19,11 @@
         <div class="input-container">
             <FluentSelect
                 TOption="CultureInfo"
-                Immediate="true"
+                ChangeOnEnterOnly="true"
                 Position="SelectPosition.Below"
                 Label="@Loc[nameof(Dialogs.SettingsDialogLanguage)]"
                 Items="@_languageOptions"
+                OptionValue="@(c => c!.Name)"
                 OptionText="@(c => c!.NativeName.Humanize())"
                 ValueChanged="@ValueChanged"
                 @bind-SelectedOption="@_selectedUiCulture"
diff --git a/src/Shared/LocaleHelpers.cs b/src/Shared/LocaleHelpers.cs
index e8a60666343..22458a095c8 100644
--- a/src/Shared/LocaleHelpers.cs
+++ b/src/Shared/LocaleHelpers.cs
@@ -9,8 +9,10 @@ namespace Aspire.Shared;
 
 internal static class LocaleHelpers
 {
+    private const int MaxCultureParentDepth = 5;
+
     // our localization list comes from https://github.com/dotnet/arcade/blob/89008f339a79931cc49c739e9dbc1a27c608b379/src/Microsoft.DotNet.XliffTasks/build/Microsoft.DotNet.XliffTasks.props#L22
-    public static readonly string[] SupportedLocales = ["en", "cs", "de", "es", "fr", "it", "ja", "ko", "pl", "pt-BR", "ru", "tr", "zh-CN", "zh-Hans", "zh-Hant"];
+    public static readonly string[] SupportedLocales = ["en", "cs", "de", "es", "fr", "it", "ja", "ko", "pl", "pt-BR", "ru", "tr", "zh-Hans", "zh-Hant"];
 
     public static SetLocaleResult TrySetLocaleOverride(string localeOverride)
     {
@@ -24,8 +26,7 @@ public static SetLocaleResult TrySetLocaleOverride(string localeOverride)
         try
         {
             var cultureInfo = new CultureInfo(localeOverride);
-            if (SupportedLocales.Contains(cultureInfo.Name) ||
-                SupportedLocales.Contains(cultureInfo.TwoLetterISOLanguageName))
+            if (IsSupportedCulture(cultureInfo))
             {
                 CultureInfo.CurrentUICulture = cultureInfo;
                 CultureInfo.CurrentCulture = cultureInfo;
@@ -42,6 +43,32 @@ public static SetLocaleResult TrySetLocaleOverride(string localeOverride)
         }
     }
 
+    private static bool IsSupportedCulture(CultureInfo cultureInfo)
+    {
+        // Check exact name and two-letter ISO language name first.
+        if (SupportedLocales.Contains(cultureInfo.Name) ||
+            SupportedLocales.Contains(cultureInfo.TwoLetterISOLanguageName))
+        {
+            return true;
+        }
+
+        // Walk the parent chain to find a supported culture.
+        // For example, zh-CN's parent is zh-Hans which is supported.
+        var current = cultureInfo.Parent;
+        var depth = 0;
+        while (current != CultureInfo.InvariantCulture && current != current.Parent && depth < MaxCultureParentDepth)
+        {
+            if (SupportedLocales.Contains(current.Name))
+            {
+                return true;
+            }
+            current = current.Parent;
+            depth++;
+        }
+
+        return false;
+    }
+
     private static bool IsKnownCulture(string cultureName)
     {
         return CultureInfo
diff --git a/tests/Aspire.Dashboard.Tests/GlobalizationHelpersTests.cs b/tests/Aspire.Dashboard.Tests/GlobalizationHelpersTests.cs
index 58816078b86..463c53df37f 100644
--- a/tests/Aspire.Dashboard.Tests/GlobalizationHelpersTests.cs
+++ b/tests/Aspire.Dashboard.Tests/GlobalizationHelpersTests.cs
@@ -3,6 +3,7 @@
 
 using System.Globalization;
 using Aspire.Dashboard.Utils;
+using Humanizer;
 using Xunit;
 
 namespace Aspire.Dashboard.Tests;
@@ -30,6 +31,16 @@ public void ExpandedLocalizedCultures_IncludesPopularCultures()
         Assert.Contains("zh-CN", supportedCultures);
     }
 
+    [Fact]
+    public void OrderedLocalizedCultures_HasUniqueDisplayNames()
+    {
+        var displayNames = GlobalizationHelpers.OrderedLocalizedCultures
+            .Select(c => c.NativeName.Humanize())
+            .ToList();
+
+        Assert.Equal(displayNames.Count, displayNames.Distinct().Count());
+    }
+
     [Theory]
     [InlineData("en", true, "en")]
     [InlineData("en-US", true, "en")]
@@ -71,6 +82,8 @@ public void TryGetKnownParentCulture_VariousCultures_ReturnsExpectedResult(strin
     [InlineData("en", "en-XX", "en")]
     [InlineData("de", "en-US", null)]
     [InlineData("zh-Hans", "en-US,en;q=0.9,zh-CN;q=0.8,zh;q=0.7", "zh-CN")]
+    [InlineData("zh-Hans", "zh-CN", "zh-CN")]
+    [InlineData("zh-Hans", "zh-CN,zh;q=0.9", "zh-CN")]
     public async Task ResolveSetCultureToAcceptedCultureAsync_MatchRequestToResult(string requestedLanguage, string acceptLanguage, string? result)
     {
         // Arrange
