diff --git a/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml b/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml
index d5027566de279..e53d32f344f7a 100644
--- a/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml
+++ b/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml
@@ -2817,6 +2817,21 @@ FullScreenEnabled:
     WebCore:
       default: false
 
+FullScreenKeyboardLock:
+  type: bool
+  status: testable
+  category: dom
+  humanReadableName: "Fullscreen API based Keyboard Lock"
+  humanReadableDescription: "Fullscreen API based Keyboard Lock"
+  condition: ENABLE(FULLSCREEN_API)
+  defaultValue:
+    WebKitLegacy:
+      default: false
+    WebKit:
+      default: false
+    WebCore:
+      default: false
+
 FullscreenRequirementForScreenOrientationLockingEnabled:
   type: bool
   status: embedder
diff --git a/Source/WebCore/dom/Element.h b/Source/WebCore/dom/Element.h
index bd7cf2c529155..58ba82e69ab83 100644
--- a/Source/WebCore/dom/Element.h
+++ b/Source/WebCore/dom/Element.h
@@ -89,6 +89,7 @@ enum class AnimationImpact : uint8_t;
 enum class EventHandling : uint8_t;
 enum class EventProcessing : uint8_t;
 enum class FullscreenNavigationUI : uint8_t;
+enum class FullscreenKeyboardLock : uint8_t;
 enum class IsSyntheticClick : bool { No, Yes };
 enum class ParserContentPolicy : uint8_t;
 enum class ResolveURLs : uint8_t { No, NoExcludingURLsForPrivacy, Yes, YesExcludingURLsForPrivacy };
diff --git a/Source/WebCore/dom/FullscreenOptions.h b/Source/WebCore/dom/FullscreenOptions.h
index 37c3b5595c936..baa2a81f9942f 100644
--- a/Source/WebCore/dom/FullscreenOptions.h
+++ b/Source/WebCore/dom/FullscreenOptions.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022 Apple Inc. All rights reserved.
+ * Copyright (C) 2022-2023 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -31,8 +31,10 @@ namespace WebCore {
 
 struct FullscreenOptions {
     enum class NavigationUI : uint8_t { Auto, Show, Hide };
+    enum class KeyboardLock : uint8_t { None, Browser, System };
 
     NavigationUI navigationUI { NavigationUI::Auto };
+    KeyboardLock keyboardLock { KeyboardLock::None };
 };
 
 } // namespace WebCore
diff --git a/Source/WebCore/dom/FullscreenOptions.idl b/Source/WebCore/dom/FullscreenOptions.idl
index c325699955f5a..46a469a3c9199 100644
--- a/Source/WebCore/dom/FullscreenOptions.idl
+++ b/Source/WebCore/dom/FullscreenOptions.idl
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2020 Apple Inc. All rights reserved.
+ * Copyright (C) 2020-2023 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -31,8 +31,17 @@
     "hide"
 };
 
+[
+    Conditional=FULLSCREEN_API, EnabledBySetting=FullScreenKeyboardLock
+] enum FullscreenKeyboardLock {
+    "none",
+    "browser",
+    "system"
+};
+
 [
     Conditional=FULLSCREEN_API
 ] dictionary FullscreenOptions {
     FullscreenNavigationUI navigationUI = "auto";
+    [EnabledBySetting=FullScreenKeyboardLock] FullscreenKeyboardLock keyboardLock = "none";
 };