diff --git a/BUCK b/BUCK
index a2eccd5adfd..0b338cccef6 100644
--- a/BUCK
+++ b/BUCK
@@ -247,6 +247,7 @@ REACT_PUBLIC_HEADERS = {
     "React/RCTInvalidating.h": RCTBASE_PATH + "RCTInvalidating.h",
     "React/RCTJSScriptLoaderModule.h": RCTBASE_PATH + "RCTJSScriptLoaderModule.h",
     "React/RCTJSStackFrame.h": RCTBASE_PATH + "RCTJSStackFrame.h",
+    "React/RCTJSThread.h": RCTBASE_PATH + "RCTJSThread.h",
     "React/RCTJavaScriptExecutor.h": RCTBASE_PATH + "RCTJavaScriptExecutor.h",
     "React/RCTJavaScriptLoader.h": RCTBASE_PATH + "RCTJavaScriptLoader.h",
     "React/RCTKeyCommands.h": RCTBASE_PATH + "RCTKeyCommands.h",
diff --git a/React/Base/RCTBridge.m b/React/Base/RCTBridge.m
index 3cc61733034..38b9cdd4695 100644
--- a/React/Base/RCTBridge.m
+++ b/React/Base/RCTBridge.m
@@ -15,6 +15,7 @@
 #import "RCTInspectorDevServerHelper.h"
 #endif
 #import "RCTDevLoadingViewProtocol.h"
+#import "RCTJSThread.h"
 #import "RCTLog.h"
 #import "RCTModuleData.h"
 #import "RCTPerformanceLogger.h"
@@ -168,15 +169,9 @@ void RCTDisableTurboModuleManagerDelegateLocking(BOOL disabled)
   NSURL *_delegateBundleURL;
 }
 
-dispatch_queue_t RCTJSThread;
-
 + (void)initialize
 {
-  static dispatch_once_t onceToken;
-  dispatch_once(&onceToken, ^{
-    // Set up JS thread
-    RCTJSThread = (id)kCFNull;
-  });
+  _RCTInitializeJSThreadConstantInternal();
 }
 
 static RCTBridge *RCTCurrentBridgeInstance = nil;
diff --git a/React/Base/RCTBridgeModule.h b/React/Base/RCTBridgeModule.h
index c823dac3dc5..fff361a58d4 100644
--- a/React/Base/RCTBridgeModule.h
+++ b/React/Base/RCTBridgeModule.h
@@ -9,6 +9,7 @@
 #import <UIKit/UIKit.h>
 
 #import <React/RCTDefines.h>
+#import <React/RCTJSThread.h>
 
 @class RCTBridge;
 @protocol RCTBridgeMethod;
@@ -42,16 +43,6 @@ typedef void (^RCTPromiseResolveBlock)(id result);
  */
 typedef void (^RCTPromiseRejectBlock)(NSString *code, NSString *message, NSError *error);
 
-/**
- * This constant can be returned from +methodQueue to force module
- * methods to be called on the JavaScript thread. This can have serious
- * implications for performance, so only use this if you're sure it's what
- * you need.
- *
- * NOTE: RCTJSThread is not a real libdispatch queue
- */
-RCT_EXTERN dispatch_queue_t RCTJSThread;
-
 RCT_EXTERN_C_BEGIN
 
 typedef struct RCTMethodInfo {
diff --git a/React/Base/RCTJSThread.h b/React/Base/RCTJSThread.h
new file mode 100644
index 00000000000..8f1bc76d2c2
--- /dev/null
+++ b/React/Base/RCTJSThread.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
+
+#import <React/RCTDefines.h>
+
+/**
+ * This constant can be returned from +methodQueue to force module
+ * methods to be called on the JavaScript thread. This can have serious
+ * implications for performance, so only use this if you're sure it's what
+ * you need.
+ *
+ * NOTE: RCTJSThread is not a real libdispatch queue
+ */
+RCT_EXTERN dispatch_queue_t RCTJSThread;
+
+/**
+ * Initializes the RCTJSThread constant.
+ * Exported because the bridgeless initialization layer needs to initialize
+ * RCTJSThread. In bridgeless mode, RCTBridge isn't accessed, and RCTJSThread
+ * therefore isn't initialized.
+ */
+RCT_EXTERN void _RCTInitializeJSThreadConstantInternal(void);
diff --git a/React/Base/RCTJSThread.m b/React/Base/RCTJSThread.m
new file mode 100644
index 00000000000..192822a8606
--- /dev/null
+++ b/React/Base/RCTJSThread.m
@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RCTJSThread.h"
+
+dispatch_queue_t RCTJSThread;
+
+void _RCTInitializeJSThreadConstantInternal(void)
+{
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    // Set up JS thread
+    RCTJSThread = (id)kCFNull;
+  });
+}