diff --git a/src/Avalonia/HandyControlDemo_Avalonia/Data/DemoInfo.json b/src/Avalonia/HandyControlDemo_Avalonia/Data/DemoInfo.json
index dfbf8ffc..24d804d2 100644
--- a/src/Avalonia/HandyControlDemo_Avalonia/Data/DemoInfo.json
+++ b/src/Avalonia/HandyControlDemo_Avalonia/Data/DemoInfo.json
@@ -6,6 +6,7 @@
     "demoItemList": [
       [ "Brush", "BrushDemo", "Brush.Brush", "", "" ],
       [ "Button", "ButtonDemo", "Brush.ButtonClick", "", "" ],
+      [ "SplitButton", "SplitButtonDemo", "Brush.ButtonClick", "", "" ],
       [ "RepeatButton", "RepeatButtonDemo", "Brush.RepeatButton", "", "" ],
       [ "ToggleButton", "ToggleButtonDemo", "Brush.Toggle", "", "" ],
       [ "ToggleSwitch", "ToggleSwitchDemo", "Brush.Toggle", "", "" ],
diff --git a/src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SplitButtonDemo.axaml b/src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SplitButtonDemo.axaml
new file mode 100644
index 00000000..e935312e
--- /dev/null
+++ b/src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SplitButtonDemo.axaml
@@ -0,0 +1,125 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:hc="https://handyorg.github.io/handycontrol"
+             x:Class="HandyControlDemo.UserControl.SplitButtonDemo"
+             Background="{DynamicResource RegionBrush}">
+    <ScrollViewer>
+        <hc:UniformSpacingPanel ChildWrapping="Wrap"
+                                Spacing="32"
+                                Margin="32">
+            <hc:UniformSpacingPanel Orientation="Vertical"
+                                    Spacing="16">
+                <TextBlock Text="SplitButton (Default)"
+                           Theme="{StaticResource TextBlockSubTitleBold}" />
+                <WrapPanel>
+                    <SplitButton Content="Default"
+                                 Margin="5">
+                        <SplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Item 1" />
+                                <MenuItem Header="Item 2" />
+                                <MenuItem Header="Item 3" />
+                            </MenuFlyout>
+                        </SplitButton.Flyout>
+                    </SplitButton>
+                    <SplitButton Content="Disabled"
+                                 IsEnabled="False"
+                                 Margin="5" />
+                    <SplitButton Content="Calendar"
+                                 Margin="5"
+                                 hc:IconElement.Geometry="{StaticResource CalendarGeometry}">
+                        <SplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Today" />
+                                <MenuItem Header="Tomorrow" />
+                            </MenuFlyout>
+                        </SplitButton.Flyout>
+                    </SplitButton>
+                </WrapPanel>
+
+                <TextBlock Text="SplitButton.Small"
+                           Theme="{StaticResource TextBlockSubTitleBold}" />
+                <WrapPanel>
+                    <SplitButton Content="Default"
+                                 Margin="5"
+                                 Theme="{StaticResource SplitButton.Small}">
+                        <SplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Item 1" />
+                                <MenuItem Header="Item 2" />
+                            </MenuFlyout>
+                        </SplitButton.Flyout>
+                    </SplitButton>
+                    <SplitButton Content="Disabled"
+                                 IsEnabled="False"
+                                 Margin="5"
+                                 Theme="{StaticResource SplitButton.Small}" />
+                    <SplitButton Content="Clock"
+                                 Margin="5"
+                                 hc:IconElement.Geometry="{StaticResource ClockGeometry}"
+                                 Theme="{StaticResource SplitButton.Small}">
+                        <SplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Now" />
+                                <MenuItem Header="Later" />
+                            </MenuFlyout>
+                        </SplitButton.Flyout>
+                    </SplitButton>
+                </WrapPanel>
+            </hc:UniformSpacingPanel>
+
+            <hc:UniformSpacingPanel Orientation="Vertical"
+                                    Spacing="16">
+                <TextBlock Text="ToggleSplitButton"
+                           Theme="{StaticResource TextBlockSubTitleBold}" />
+                <WrapPanel>
+                    <ToggleSplitButton Content="Toggle"
+                                       Margin="5">
+                        <ToggleSplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Option A" />
+                                <MenuItem Header="Option B" />
+                            </MenuFlyout>
+                        </ToggleSplitButton.Flyout>
+                    </ToggleSplitButton>
+                    <ToggleSplitButton Content="Checked"
+                                       IsChecked="True"
+                                       Margin="5">
+                        <ToggleSplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Option A" />
+                                <MenuItem Header="Option B" />
+                            </MenuFlyout>
+                        </ToggleSplitButton.Flyout>
+                    </ToggleSplitButton>
+                    <ToggleSplitButton Content="Disabled"
+                                       IsEnabled="False"
+                                       Margin="5" />
+                </WrapPanel>
+
+                <TextBlock Text="ToggleSplitButton.Small"
+                           Theme="{StaticResource TextBlockSubTitleBold}" />
+                <WrapPanel>
+                    <ToggleSplitButton Content="Toggle"
+                                       Margin="5"
+                                       Theme="{StaticResource ToggleSplitButton.Small}">
+                        <ToggleSplitButton.Flyout>
+                            <MenuFlyout>
+                                <MenuItem Header="Option A" />
+                                <MenuItem Header="Option B" />
+                            </MenuFlyout>
+                        </ToggleSplitButton.Flyout>
+                    </ToggleSplitButton>
+                    <ToggleSplitButton Content="Checked"
+                                       IsChecked="True"
+                                       Margin="5"
+                                       Theme="{StaticResource ToggleSplitButton.Small}" />
+                    <ToggleSplitButton Content="Disabled"
+                                       IsEnabled="False"
+                                       Margin="5"
+                                       Theme="{StaticResource ToggleSplitButton.Small}" />
+                </WrapPanel>
+            </hc:UniformSpacingPanel>
+        </hc:UniformSpacingPanel>
+    </ScrollViewer>
+</UserControl>
diff --git a/src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SplitButtonDemo.axaml.cs b/src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SplitButtonDemo.axaml.cs
new file mode 100644
index 00000000..f7b1e95b
--- /dev/null
+++ b/src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SplitButtonDemo.axaml.cs
@@ -0,0 +1,9 @@
+namespace HandyControlDemo.UserControl;
+
+public partial class SplitButtonDemo : Avalonia.Controls.UserControl
+{
+    public SplitButtonDemo()
+    {
+        InitializeComponent();
+    }
+}
diff --git a/src/Avalonia/HandyControl_Avalonia/Themes/Styles/MergedStyles.axaml b/src/Avalonia/HandyControl_Avalonia/Themes/Styles/MergedStyles.axaml
index 94cf86b7..d13324de 100644
--- a/src/Avalonia/HandyControl_Avalonia/Themes/Styles/MergedStyles.axaml
+++ b/src/Avalonia/HandyControl_Avalonia/Themes/Styles/MergedStyles.axaml
@@ -32,6 +32,7 @@
                 <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/UserControl.axaml" />
                 <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/Window.axaml" />
                 <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/Button.axaml" />
+                <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/SplitButton.axaml" />
                 <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/HyperlinkButton.axaml" />
                 <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/RepeatButton.axaml" />
                 <MergeResourceInclude Source="avares://HandyControl/Themes/Styles/ToggleButton.axaml" />
diff --git a/src/Avalonia/HandyControl_Avalonia/Themes/Styles/SplitButton.axaml b/src/Avalonia/HandyControl_Avalonia/Themes/Styles/SplitButton.axaml
new file mode 100644
index 00000000..15251239
--- /dev/null
+++ b/src/Avalonia/HandyControl_Avalonia/Themes/Styles/SplitButton.axaml
@@ -0,0 +1,207 @@
+<ResourceDictionary xmlns="https://github.com/avaloniaui"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    x:ClassModifier="internal"
+                    xmlns:hc="clr-namespace:HandyControl.Controls">
+
+    <!-- Inner button theme used by SplitButton's PART_PrimaryButton / PART_SecondaryButton.
+         Reacts to its own pointer/pressed states; outer SplitButton can also overlay state via Tag. -->
+    <ControlTheme x:Key="SplitButtonComponent"
+                  TargetType="Button">
+        <Setter Property="HorizontalContentAlignment"
+                Value="Center" />
+        <Setter Property="VerticalContentAlignment"
+                Value="Center" />
+        <Setter Property="Template">
+            <ControlTemplate>
+                <Border x:Name="border"
+                        Background="{TemplateBinding Background}"
+                        BorderBrush="{TemplateBinding BorderBrush}"
+                        BorderThickness="{TemplateBinding BorderThickness}"
+                        CornerRadius="{TemplateBinding CornerRadius}">
+                    <StackPanel Orientation="Horizontal"
+                                HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
+                                Margin="{TemplateBinding Padding}">
+                        <Path Width="{TemplateBinding hc:IconElement.Width}"
+                              Height="{TemplateBinding hc:IconElement.Height}"
+                              Fill="{TemplateBinding Foreground}"
+                              IsVisible="{Binding Path=(hc:IconElement.Geometry), RelativeSource={RelativeSource TemplatedParent}, Converter={x:Static ObjectConverters.IsNotNull}}"
+                              Stretch="Uniform"
+                              Data="{TemplateBinding hc:IconElement.Geometry}" />
+                        <ContentPresenter RecognizesAccessKey="True"
+                                          VerticalAlignment="Center"
+                                          Content="{TemplateBinding Content}"
+                                          ContentTemplate="{TemplateBinding ContentTemplate}"
+                                          IsVisible="{Binding $self.Content, Converter={x:Static ObjectConverters.IsNotNull}}"
+                                          Margin="{Binding Path=(hc:IconElement.Geometry), RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource GeometrySpacingConverter}, ConverterParameter='6,0,0,0'}" />
+                    </StackPanel>
+                </Border>
+            </ControlTemplate>
+        </Setter>
+
+        <Style Selector="^:pointerover /template/ Border#border">
+            <Setter Property="Background"
+                    Value="{DynamicResource SecondaryRegionBrush}" />
+        </Style>
+
+        <Style Selector="^:pressed /template/ Border#border">
+            <Setter Property="Background"
+                    Value="{DynamicResource BorderBrush}" />
+        </Style>
+
+        <Style Selector="^[Tag=flyout-open] /template/ Border#border">
+            <Setter Property="Background"
+                    Value="{DynamicResource BorderBrush}" />
+        </Style>
+
+        <Style Selector="^[Tag=checked] /template/ Border#border">
+            <Setter Property="Background"
+                    Value="{DynamicResource PrimaryBrush}" />
+        </Style>
+
+        <Style Selector="^[Tag=checked]">
+            <Setter Property="Foreground"
+                    Value="{DynamicResource TextIconBrush}" />
+        </Style>
+    </ControlTheme>
+
+    <!-- SplitButton base: HC default look -->
+    <ControlTheme x:Key="SplitButtonBaseStyle"
+                  TargetType="SplitButton">
+        <Setter Property="Height"
+                Value="{StaticResource DefaultControlHeight}" />
+        <Setter Property="Padding"
+                Value="{StaticResource DefaultControlPadding}" />
+        <Setter Property="HorizontalAlignment"
+                Value="Left" />
+        <Setter Property="VerticalAlignment"
+                Value="Center" />
+        <Setter Property="HorizontalContentAlignment"
+                Value="Center" />
+        <Setter Property="VerticalContentAlignment"
+                Value="Center" />
+        <Setter Property="Background"
+                Value="{DynamicResource RegionBrush}" />
+        <Setter Property="Foreground"
+                Value="{DynamicResource PrimaryTextBrush}" />
+        <Setter Property="BorderBrush"
+                Value="{DynamicResource BorderBrush}" />
+        <Setter Property="BorderThickness"
+                Value="1" />
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="{StaticResource DefaultCornerRadius}" />
+        <Setter Property="CornerRadius"
+                Value="{Binding $self.(hc:BorderElement.CornerRadius)}" />
+        <Setter Property="Template">
+            <ControlTemplate>
+                <Grid ColumnDefinitions="*,Auto,Auto">
+                    <Button x:Name="PART_PrimaryButton"
+                            Grid.Column="0"
+                            Theme="{StaticResource SplitButtonComponent}"
+                            Foreground="{TemplateBinding Foreground}"
+                            Background="{TemplateBinding Background}"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource ThicknessSplitConverter}, ConverterParameter='1,1,0,1'}"
+                            Content="{TemplateBinding Content}"
+                            ContentTemplate="{TemplateBinding ContentTemplate}"
+                            Command="{TemplateBinding Command}"
+                            CommandParameter="{TemplateBinding CommandParameter}"
+                            CornerRadius="{TemplateBinding CornerRadius, Converter={StaticResource CornerRadiusSplitConverter}, ConverterParameter='1,0,0,1'}"
+                            FontFamily="{TemplateBinding FontFamily}"
+                            FontSize="{TemplateBinding FontSize}"
+                            FontWeight="{TemplateBinding FontWeight}"
+                            HorizontalAlignment="Stretch"
+                            VerticalAlignment="Stretch"
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                            Padding="{TemplateBinding Padding}"
+                            hc:IconElement.Geometry="{TemplateBinding hc:IconElement.Geometry}"
+                            hc:IconElement.Width="{TemplateBinding hc:IconElement.Width}"
+                            hc:IconElement.Height="{TemplateBinding hc:IconElement.Height}"
+                            Focusable="False"
+                            KeyboardNavigation.IsTabStop="False" />
+
+                    <Border x:Name="SeparatorBorder"
+                            Grid.Column="1"
+                            Width="1"
+                            Background="{TemplateBinding BorderBrush}" />
+
+                    <Button x:Name="PART_SecondaryButton"
+                            Grid.Column="2"
+                            Theme="{StaticResource SplitButtonComponent}"
+                            MinWidth="28"
+                            Foreground="{TemplateBinding Foreground}"
+                            Background="{TemplateBinding Background}"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource ThicknessSplitConverter}, ConverterParameter='0,1,1,1'}"
+                            CornerRadius="{TemplateBinding CornerRadius, Converter={StaticResource CornerRadiusSplitConverter}, ConverterParameter='0,1,1,0'}"
+                            Padding="0"
+                            HorizontalContentAlignment="Center"
+                            VerticalContentAlignment="Center"
+                            HorizontalAlignment="Stretch"
+                            VerticalAlignment="Stretch"
+                            Focusable="False"
+                            KeyboardNavigation.IsTabStop="False">
+                        <Path Width="8"
+                              Height="5"
+                              Stretch="Uniform"
+                              Fill="{TemplateBinding Foreground}"
+                              Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z" />
+                    </Button>
+
+                    <Border Name="CheckedMask"
+                            Grid.Column="0"
+                            Grid.ColumnSpan="3"
+                            Margin="-1"
+                            CornerRadius="{TemplateBinding CornerRadius}"
+                            BorderThickness="4"
+                            BorderBrush="{DynamicResource DarkMaskBrush}"
+                            IsHitTestVisible="False"
+                            IsVisible="False" />
+                </Grid>
+            </ControlTemplate>
+        </Setter>
+
+        <Style Selector="^:disabled">
+            <Setter Property="Opacity"
+                    Value="0.4" />
+        </Style>
+
+        <!-- :checked only triggers for ToggleSplitButton (SplitButton.InternalIsChecked is always false) -->
+        <Style Selector="^:checked /template/ Border#CheckedMask">
+            <Setter Property="IsVisible"
+                    Value="True" />
+        </Style>
+
+        <!-- Mirror SplitButton pseudo-state into the secondary inner button via Tag,
+             so :flyout-open visually highlights only the dropdown side. -->
+        <Style Selector="^:flyout-open /template/ Button#PART_SecondaryButton">
+            <Setter Property="Tag"
+                    Value="flyout-open" />
+        </Style>
+    </ControlTheme>
+
+    <ControlTheme x:Key="{x:Type SplitButton}"
+                  BasedOn="{StaticResource SplitButtonBaseStyle}"
+                  TargetType="SplitButton" />
+
+    <ControlTheme x:Key="SplitButton.Small"
+                  BasedOn="{StaticResource SplitButtonBaseStyle}"
+                  TargetType="SplitButton">
+        <Setter Property="Height"
+                Value="20" />
+        <Setter Property="Padding"
+                Value="6,1" />
+        <Setter Property="hc:IconElement.Height"
+                Value="12" />
+    </ControlTheme>
+
+    <!-- ToggleSplitButton uses StyleKeyOverride => typeof(SplitButton), so it inherits the
+         SplitButton default theme automatically. The :checked dark mask is defined in
+         SplitButtonBaseStyle and only triggers when InternalIsChecked == true (i.e. on
+         ToggleSplitButton instances). -->
+
+    <ControlTheme x:Key="ToggleSplitButton.Small"
+                  BasedOn="{StaticResource SplitButton.Small}"
+                  TargetType="ToggleSplitButton" />
+</ResourceDictionary>