diff --git a/src/Uno.UI.FluentTheme/Resources/Version2/PriorityDefault/ComboBox_themeresources.xaml b/src/Uno.UI.FluentTheme/Resources/Version2/PriorityDefault/ComboBox_themeresources.xaml
index 17c5ce3f888d..6d887a0feaa0 100644
--- a/src/Uno.UI.FluentTheme/Resources/Version2/PriorityDefault/ComboBox_themeresources.xaml
+++ b/src/Uno.UI.FluentTheme/Resources/Version2/PriorityDefault/ComboBox_themeresources.xaml
@@ -9,7 +9,11 @@
   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   xmlns:controls="using:Microsoft.UI.Xaml.Controls"
   xmlns:animatedVisuals="using:Microsoft.UI.Xaml.Controls.AnimatedVisuals"
-  xmlns:primitives="using:Microsoft.UI.Xaml.Controls.Primitives">
+  xmlns:primitives="using:Microsoft.UI.Xaml.Controls.Primitives"
+  xmlns:not_win="http://uno.ui/not_win"
+  xmlns:win="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+  mc:ignorable="not_win">
     <ResourceDictionary.ThemeDictionaries>
         <ResourceDictionary x:Key="Default">
             <StaticResource x:Key="ComboBoxItemForeground" ResourceKey="TextFillColorPrimaryBrush" />
@@ -391,7 +395,11 @@
         <Setter Property="PlaceholderForeground" Value="{ThemeResource ComboBoxPlaceHolderForeground}" />
         <Setter Property="Foreground" Value="{ThemeResource ComboBoxForeground}" />
         <Setter Property="Background" Value="{ThemeResource ComboBoxBackground}" />
-        <Setter Property="BorderBrush" Value="{ThemeResource ComboBoxBorderBrush}" />
+        
+        <!-- Uno specific (LinearGradientBrush borders): Use solid border brush -->
+        <win:Setter Property="BorderBrush" Value="{ThemeResource ComboBoxBorderBrush}" />
+        <not_win:Setter Property="BorderBrush" Value="{ThemeResource ControlStrokeColorDefaultBrush}" />
+        
         <Setter Property="BorderThickness" Value="{ThemeResource ComboBoxBorderThemeThickness}" />
         <Setter Property="TabNavigation" Value="Once" />
         <contract7Present:Setter Property="TextBoxStyle" Value="{StaticResource ComboBoxTextBoxStyle}" />
@@ -443,9 +451,9 @@
                                         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="Background">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBackgroundPointerOver}" />
                                         </ObjectAnimationUsingKeyFrames>
-                                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
+                                        <win:ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBorderBrushPointerOver}" />
-                                        </ObjectAnimationUsingKeyFrames>
+                                        </win:ObjectAnimationUsingKeyFrames>
                                         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxForegroundPointerOver}" />
                                         </ObjectAnimationUsingKeyFrames>
@@ -467,6 +475,10 @@
                                         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBorderBrushPressed}" />
                                         </ObjectAnimationUsingKeyFrames>
+                                        <!-- Uno specific (LinearGradientBrush borders): Hide bottom border overlay -->
+                                        <not_win:ObjectAnimationUsingKeyFrames Storyboard.TargetName="BottomBorderElement" Storyboard.TargetProperty="Visibility">
+                                            <DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
+                                        </not_win:ObjectAnimationUsingKeyFrames>
                                         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxForegroundPressed}" />
                                         </ObjectAnimationUsingKeyFrames>
@@ -488,6 +500,10 @@
                                         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBorderBrushDisabled}" />
                                         </ObjectAnimationUsingKeyFrames>
+                                        <!-- Uno specific (LinearGradientBrush borders): Hide bottom border overlay -->
+                                        <not_win:ObjectAnimationUsingKeyFrames Storyboard.TargetName="BottomBorderElement" Storyboard.TargetProperty="Visibility">
+                                            <DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
+                                        </not_win:ObjectAnimationUsingKeyFrames>
                                         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HeaderContentPresenter" Storyboard.TargetProperty="Foreground">
                                             <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxHeaderForegroundDisabled}" />
                                         </ObjectAnimationUsingKeyFrames>
@@ -665,6 +681,16 @@
                             Control.IsTemplateFocusTarget="True"
                             MinWidth="{ThemeResource ComboBoxThemeMinWidth}" />
 
+                        <!-- Uno specific (LinearGradientBrush borders): Simulates bottom border -->
+                        <not_win:Border x:Name="BottomBorderElement"
+                            Grid.Row="1"
+                            Grid.Column="0"
+                            Grid.ColumnSpan="2"                        
+                            BorderThickness="0,0,0,1"
+                            contract7Present:CornerRadius="{TemplateBinding CornerRadius}"
+                            contract7NotPresent:CornerRadius="{ThemeResource ControlCornerRadius}"
+                            BorderBrush="{ThemeResource UnoElevationBorderOverlayBrush}" />
+
                         <Rectangle x:Name="Pill"
                             Style="{StaticResource ComboBoxItemPill}"
                             Margin="1,0,0,0"
diff --git a/src/Uno.UI.FluentTheme/themeresources_v2.xaml b/src/Uno.UI.FluentTheme/themeresources_v2.xaml
index d68cb6ac13ee..a511b335c134 100644
--- a/src/Uno.UI.FluentTheme/themeresources_v2.xaml
+++ b/src/Uno.UI.FluentTheme/themeresources_v2.xaml
@@ -13335,7 +13335,9 @@
     <Setter Property="PlaceholderForeground" Value="{ThemeResource ComboBoxPlaceHolderForeground}" />
     <Setter Property="Foreground" Value="{ThemeResource ComboBoxForeground}" />
     <Setter Property="Background" Value="{ThemeResource ComboBoxBackground}" />
-    <Setter Property="BorderBrush" Value="{ThemeResource ComboBoxBorderBrush}" />
+    <!-- Uno specific (LinearGradientBrush borders): Use solid border brush -->
+    <win:Setter Property="BorderBrush" Value="{ThemeResource ComboBoxBorderBrush}" />
+    <not_win:Setter Property="BorderBrush" Value="{ThemeResource ControlStrokeColorDefaultBrush}" />
     <Setter Property="BorderThickness" Value="{ThemeResource ComboBoxBorderThemeThickness}" />
     <Setter Property="TabNavigation" Value="Once" />
     <contract7Present:Setter Property="TextBoxStyle" Value="{StaticResource ComboBoxTextBoxStyle}" />
@@ -13387,9 +13389,9 @@
                     <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="Background">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBackgroundPointerOver}" />
                     </ObjectAnimationUsingKeyFrames>
-                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
+                    <win:ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBorderBrushPointerOver}" />
-                    </ObjectAnimationUsingKeyFrames>
+                    </win:ObjectAnimationUsingKeyFrames>
                     <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxForegroundPointerOver}" />
                     </ObjectAnimationUsingKeyFrames>
@@ -13411,6 +13413,10 @@
                     <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBorderBrushPressed}" />
                     </ObjectAnimationUsingKeyFrames>
+                    <!-- Uno specific (LinearGradientBrush borders): Hide bottom border overlay -->
+                    <not_win:ObjectAnimationUsingKeyFrames Storyboard.TargetName="BottomBorderElement" Storyboard.TargetProperty="Visibility">
+                      <DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
+                    </not_win:ObjectAnimationUsingKeyFrames>
                     <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxForegroundPressed}" />
                     </ObjectAnimationUsingKeyFrames>
@@ -13432,6 +13438,10 @@
                     <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Background" Storyboard.TargetProperty="BorderBrush">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxBorderBrushDisabled}" />
                     </ObjectAnimationUsingKeyFrames>
+                    <!-- Uno specific (LinearGradientBrush borders): Hide bottom border overlay -->
+                    <not_win:ObjectAnimationUsingKeyFrames Storyboard.TargetName="BottomBorderElement" Storyboard.TargetProperty="Visibility">
+                      <DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
+                    </not_win:ObjectAnimationUsingKeyFrames>
                     <ObjectAnimationUsingKeyFrames Storyboard.TargetName="HeaderContentPresenter" Storyboard.TargetProperty="Foreground">
                       <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource ComboBoxHeaderForegroundDisabled}" />
                     </ObjectAnimationUsingKeyFrames>
@@ -13553,6 +13563,8 @@
             <ContentPresenter x:Name="HeaderContentPresenter" Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" Content="{TemplateBinding Header}" ContentTemplate="{TemplateBinding HeaderTemplate}" FlowDirection="{TemplateBinding FlowDirection}" Foreground="{ThemeResource ComboBoxHeaderForeground}" FontWeight="{ThemeResource ComboBoxHeaderThemeFontWeight}" LineHeight="20" Margin="{ThemeResource ComboBoxTopHeaderMargin}" TextWrapping="Wrap" VerticalAlignment="Top" Visibility="Collapsed" x:DeferLoadStrategy="Lazy" />
             <Border x:Name="HighlightBackground" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" Margin="-4" Background="{ThemeResource ComboBoxBackgroundFocused}" BorderBrush="{ThemeResource ComboBoxBackgroundBorderBrushFocused}" BorderThickness="{StaticResource ComboBoxBackgroundBorderThicknessFocused}" contract7Present:CornerRadius="{StaticResource ComboBoxHiglightBorderCornerRadius}" contract7NotPresent:CornerRadius="{ThemeResource ControlCornerRadius}" Opacity="0" />
             <Border x:Name="Background" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" contract7Present:Translation="0,0,1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" contract7Present:CornerRadius="{TemplateBinding CornerRadius}" contract7NotPresent:CornerRadius="{ThemeResource ControlCornerRadius}" Control.IsTemplateFocusTarget="True" MinWidth="{ThemeResource ComboBoxThemeMinWidth}" />
+            <!-- Uno specific (LinearGradientBrush borders): Simulates bottom border -->
+            <not_win:Border x:Name="BottomBorderElement" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2" BorderThickness="0,0,0,1" contract7Present:CornerRadius="{TemplateBinding CornerRadius}" contract7NotPresent:CornerRadius="{ThemeResource ControlCornerRadius}" BorderBrush="{ThemeResource UnoElevationBorderOverlayBrush}" />
             <Rectangle x:Name="Pill" Style="{StaticResource ComboBoxItemPill}" Margin="1,0,0,0" Grid.Row="1" Grid.Column="0" Opacity="0">
               <Rectangle.RenderTransform>
                 <CompositeTransform x:Name="PillTransform" ScaleY="1" />