diff --git a/src/Avalonia.Base/StyledElement.cs b/src/Avalonia.Base/StyledElement.cs
index 711d17d014..d1b960390c 100644
--- a/src/Avalonia.Base/StyledElement.cs
+++ b/src/Avalonia.Base/StyledElement.cs
@@ -21,7 +21,6 @@ namespace Avalonia
     /// Extends an <see cref="Animatable"/> with the following features:
     /// 
     /// - An inherited <see cref="DataContext"/>.
-    /// - Implements <see cref="IStyleable"/> to allow styling to work on the styled element.
     /// - Implements <see cref="ILogical"/> to form part of a logical tree.
     /// - A collection of class strings for custom styling.
     /// </summary>
@@ -35,10 +34,7 @@ namespace Avalonia
         ISetInheritanceParent,
         ISupportInitialize,
         INamed,
-        IAvaloniaListItemValidator<ILogical>,
-#pragma warning disable CS0618 // Type or member is obsolete
-        IStyleable
-#pragma warning restore CS0618 // Type or member is obsolete
+        IAvaloniaListItemValidator<ILogical>
     {
         /// <summary>
         /// Defines the <see cref="DataContext"/> property.
@@ -330,9 +326,6 @@ namespace Avalonia
         bool IResourceNode.HasResources => (_resources?.HasResources ?? false) ||
             (((IResourceNode?)_styles)?.HasResources ?? false);
 
-        /// <inheritdoc/>
-        IAvaloniaReadOnlyList<string> IStyleable.Classes => Classes;
-
         /// <inheritdoc/>
         bool IStyleHost.IsStylesInitialized => _styles != null;
 
@@ -668,7 +661,7 @@ namespace Avalonia
             // If the Theme property is not set, try to find a ControlTheme resource with our StyleKey.
             if (_implicitTheme is null)
             {
-                var key = GetStyleKey(this);
+                var key = StyleKey;
 
                 if (this.TryFindResource(key, out var value) && value is ControlTheme t)
                     _implicitTheme = t;
@@ -699,22 +692,6 @@ namespace Avalonia
             }
         }
 
-        /// <summary>
-        /// Internal getter for <see cref="IStyleable.StyleKey"/> so that we only need to suppress the obsolete
-        /// warning in one place.
-        /// </summary>
-        /// <param name="e">The element</param>
-        /// <remarks>
-        /// <see cref="IStyleable"/> is obsolete and will be removed in a future version, but for backwards
-        /// compatibility we need to support code which overrides <see cref="IStyleable.StyleKey"/>.
-        /// </remarks>
-        internal static Type GetStyleKey(StyledElement e)
-        {
-#pragma warning disable CS0618 // Type or member is obsolete
-            return ((IStyleable)e).StyleKey;
-#pragma warning restore CS0618 // Type or member is obsolete
-        }
-
         private static void DataContextNotifying(AvaloniaObject o, bool updateStarted)
         {
             if (o is StyledElement element)
diff --git a/src/Avalonia.Base/Styling/ControlTheme.cs b/src/Avalonia.Base/Styling/ControlTheme.cs
index fbd869a9a7..138c2f9de5 100644
--- a/src/Avalonia.Base/Styling/ControlTheme.cs
+++ b/src/Avalonia.Base/Styling/ControlTheme.cs
@@ -50,7 +50,7 @@ namespace Avalonia.Styling
             using var activity = Diagnostic.AttachingStyle()?
                 .AddTag(Diagnostic.Tags.Style, this);
             
-            if (HasSettersOrAnimations && TargetType.IsAssignableFrom(StyledElement.GetStyleKey(target)))
+            if (HasSettersOrAnimations && TargetType.IsAssignableFrom(target.StyleKey))
             {
                 Attach(target, null, type, true);
                 activity?.AddTag(Diagnostic.Tags.SelectorResult, SelectorMatchResult.AlwaysThisType);
diff --git a/src/Avalonia.Base/Styling/IStyleable.cs b/src/Avalonia.Base/Styling/IStyleable.cs
deleted file mode 100644
index 0768669905..0000000000
--- a/src/Avalonia.Base/Styling/IStyleable.cs
+++ /dev/null
@@ -1,28 +0,0 @@
-using System;
-using Avalonia.Collections;
-
-namespace Avalonia.Styling
-{
-    /// <summary>
-    /// Interface for styleable elements.
-    /// </summary>
-    [Obsolete("This interface may be removed in 12.0. Use StyledElement, or override StyledElement.StyleKeyOverride to override the StyleKey for a class.")]
-    public interface IStyleable : INamed
-    {
-        /// <summary>
-        /// Gets the list of classes for the control.
-        /// </summary>
-        IAvaloniaReadOnlyList<string> Classes { get; }
-
-        /// <summary>
-        /// Gets the type by which the control is styled.
-        /// </summary>
-        [Obsolete("Override StyledElement.StyleKeyOverride instead.")]
-        Type StyleKey { get; }
-
-        /// <summary>
-        /// Gets the template parent of this element if the control comes from a template.
-        /// </summary>
-        AvaloniaObject? TemplatedParent { get; }
-    }
-}
diff --git a/src/Avalonia.Base/Styling/NestingSelector.cs b/src/Avalonia.Base/Styling/NestingSelector.cs
index 4f6920c224..07fc24b644 100644
--- a/src/Avalonia.Base/Styling/NestingSelector.cs
+++ b/src/Avalonia.Base/Styling/NestingSelector.cs
@@ -23,7 +23,7 @@ namespace Avalonia.Styling
             {
                 if (theme.TargetType is null)
                     throw new InvalidOperationException("ControlTheme has no TargetType.");
-                return theme.TargetType.IsAssignableFrom(StyledElement.GetStyleKey(control)) ?
+                return theme.TargetType.IsAssignableFrom(control.StyleKey) ?
                     SelectorMatch.AlwaysThisType :
                     SelectorMatch.NeverThisType;
             }
@@ -31,7 +31,7 @@ namespace Avalonia.Styling
             {
                 if (queryTheme.TargetType is null)
                     throw new InvalidOperationException("ControlTheme has no TargetType.");
-                return queryTheme.TargetType.IsAssignableFrom(StyledElement.GetStyleKey(control)) ?
+                return queryTheme.TargetType.IsAssignableFrom(control.StyleKey) ?
                     SelectorMatch.AlwaysThisType :
                     SelectorMatch.NeverThisType;
             }
diff --git a/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs b/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs
index 4fba8c02c6..4f78d91a38 100644
--- a/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs
+++ b/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs
@@ -93,7 +93,7 @@ namespace Avalonia.Styling
         {
             if (TargetType != null)
             {
-                var controlType = StyledElement.GetStyleKey(control) ?? control.GetType();
+                var controlType = control.StyleKey ?? control.GetType();
 
                 if (IsConcreteType)
                 {
diff --git a/src/Avalonia.Controls/ItemsControl.cs b/src/Avalonia.Controls/ItemsControl.cs
index 0c3e908bbf..a9cf4ca8d8 100644
--- a/src/Avalonia.Controls/ItemsControl.cs
+++ b/src/Avalonia.Controls/ItemsControl.cs
@@ -720,7 +720,7 @@ namespace Avalonia.Controls
             {
                 var itemContainerTheme = ItemContainerTheme;
 
-                if (itemContainerTheme?.TargetType?.IsAssignableFrom(GetStyleKey(container)) == true)
+                if (itemContainerTheme?.TargetType?.IsAssignableFrom(container.StyleKey) == true)
                 {
                     // We have an ItemContainerTheme and it matches the container. Set the Theme
                     // property, and mark the container as having had ItemContainerTheme applied.