diff --git a/packages/react-native/React/Base/RCTBridgeDelegate.h b/packages/react-native/React/Base/RCTBridgeDelegate.h
index 0e081964bc2ec2..901531f7933f39 100644
--- a/packages/react-native/React/Base/RCTBridgeDelegate.h
+++ b/packages/react-native/React/Base/RCTBridgeDelegate.h
@@ -18,7 +18,7 @@
  * When running from a locally bundled JS file, this should be a `file://` url
  * pointing to a path inside the app resources, e.g. `file://.../main.jsbundle`.
  */
-- (NSURL *)sourceURLForBridge:(RCTBridge *)bridge;
+- (NSURL *__nullable)sourceURLForBridge:(RCTBridge *)bridge;
 
 @optional
 
diff --git a/packages/react-native/React/Base/RCTBundleURLProvider.h b/packages/react-native/React/Base/RCTBundleURLProvider.h
index bd627816167872..79910ecf7c3b69 100644
--- a/packages/react-native/React/Base/RCTBundleURLProvider.h
+++ b/packages/react-native/React/Base/RCTBundleURLProvider.h
@@ -9,7 +9,7 @@
 
 #import "RCTDefines.h"
 
-RCT_EXTERN NSString *const RCTBundleURLProviderUpdatedNotification;
+RCT_EXTERN NSString *_Nonnull const RCTBundleURLProviderUpdatedNotification;
 RCT_EXTERN const NSUInteger kRCTBundleURLProviderDefaultPort;
 
 #if RCT_DEV_MENU | RCT_PACKAGER_LOADING_FUNCTIONALITY
@@ -22,6 +22,8 @@ RCT_EXTERN const NSUInteger kRCTBundleURLProviderDefaultPort;
 RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
 #endif
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface RCTBundleURLProvider : NSObject
 
 /**
@@ -52,44 +54,44 @@ RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
  * The port is optional, if not specified, kRCTBundleURLProviderDefaultPort will be used
  * The scheme is also optional, if not specified, a default http protocol will be used
  */
-+ (BOOL)isPackagerRunning:(NSString *)hostPort scheme:(NSString *)scheme;
++ (BOOL)isPackagerRunning:(NSString *)hostPort scheme:(NSString *__nullable)scheme;
 
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
  * the fallback offline JS bundle if the packager is not running.
  */
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackURLProvider:(NSURL * (^)(void))fallbackURLProvider;
+- (NSURL *__nullable)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackURLProvider:(NSURL *__nullable (^)(void))fallbackURLProvider;
 
 /**
  * Returns the jsBundleURL for a given split bundle entrypoint in development
  */
-- (NSURL *)jsBundleURLForSplitBundleRoot:(NSString *)bundleRoot;
+- (NSURL *__nullable)jsBundleURLForSplitBundleRoot:(NSString *)bundleRoot;
 
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
  * the fallback offline JS bundle if the packager is not running.
  * if extension is nil, "jsbundle" will be used.
  */
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackExtension:(NSString *)extension;
+- (NSURL *__nullable)jsBundleURLForBundleRoot:(NSString *)bundleRoot fallbackExtension:(NSString *__nullable)extension;
 
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
  * the fallback offline JS bundle if the packager is not running.
  */
-- (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot;
+- (NSURL *__nullable)jsBundleURLForBundleRoot:(NSString *)bundleRoot;
 
 /**
  * Returns the jsBundleURL for a given bundle entrypoint and
  * the fallback offline JS bundle. If extension is nil,
  * "jsbundle" will be used.
  */
-- (NSURL *)jsBundleURLForFallbackExtension:(NSString *)extension;
+- (NSURL *__nullable)jsBundleURLForFallbackExtension:(NSString *)extension;
 
 /**
  * Returns the resourceURL for a given bundle entrypoint and
  * the fallback offline resource file if the packager is not running.
  */
-- (NSURL *)resourceURLForResourceRoot:(NSString *)root
+- (NSURL *__nullable)resourceURLForResourceRoot:(NSString *)root
                          resourceName:(NSString *)name
                     resourceExtension:(NSString *)extension
                         offlineBundle:(NSBundle *)offlineBundle;
@@ -124,15 +126,15 @@ RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
  * - runModule: When true, will run the main module after defining all modules. This is used in the main bundle but not
  *     in split bundles.
  */
-+ (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot
++ (NSURL *__nullable)jsBundleURLForBundleRoot:(NSString *)bundleRoot
                        packagerHost:(NSString *)packagerHost
                           enableDev:(BOOL)enableDev
                  enableMinification:(BOOL)enableMinification
                     inlineSourceMap:(BOOL)inlineSourceMap;
 
-+ (NSURL *)jsBundleURLForBundleRoot:(NSString *)bundleRoot
++ (NSURL *__nullable)jsBundleURLForBundleRoot:(NSString *)bundleRoot
                        packagerHost:(NSString *)packagerHost
-                     packagerScheme:(NSString *)scheme
+                     packagerScheme:(NSString *__nullable)scheme
                           enableDev:(BOOL)enableDev
                  enableMinification:(BOOL)enableMinification
                     inlineSourceMap:(BOOL)inlineSourceMap
@@ -145,8 +147,8 @@ RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
  */
 + (NSURL *)resourceURLForResourcePath:(NSString *)path
                          packagerHost:(NSString *)packagerHost
-                               scheme:(NSString *)scheme
-                                query:(NSString *)query
+                               scheme:(NSString *__nullable)scheme
+                                query:(NSString *__nullable)query
     __deprecated_msg("Use version with queryItems parameter instead");
 
 /**
@@ -157,6 +159,8 @@ RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
 + (NSURL *)resourceURLForResourcePath:(NSString *)path
                          packagerHost:(NSString *)packagerHost
                                scheme:(NSString *)scheme
-                           queryItems:(NSArray<NSURLQueryItem *> *)queryItems;
+                           queryItems:(NSArray<NSURLQueryItem *> *__nullable)queryItems;
 
 @end
+
+NS_ASSUME_NONNULL_END