diff --git a/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.h b/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.h
index 603e795f1778ed..917e9544ee9be4 100644
--- a/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.h
+++ b/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.h
@@ -39,7 +39,6 @@ typedef std::shared_ptr<facebook::react::JSEngineInstance> (^RCTHostJSEngineProv
 
 @protocol RCTHostDelegate <NSObject>
 
-- (std::shared_ptr<facebook::react::JSEngineInstance>)getJSEngine;
 - (NSURL *)getBundleURL;
 - (std::shared_ptr<facebook::react::ContextContainer>)createContextContainer;
 
@@ -61,8 +60,7 @@ typedef std::shared_ptr<facebook::react::JSEngineInstance> (^RCTHostJSEngineProv
 - (instancetype)initWithHostDelegate:(id<RCTHostDelegate>)hostDelegate
           turboModuleManagerDelegate:(id<RCTTurboModuleManagerDelegate>)turboModuleManagerDelegate
                  bindingsInstallFunc:(facebook::react::ReactInstance::BindingsInstallFunc)bindingsInstallFunc
-                    jsEngineProvider:(nullable RCTHostJSEngineProvider)jsEngineProvider NS_DESIGNATED_INITIALIZER
-    FB_OBJC_DIRECT;
+                    jsEngineProvider:(RCTHostJSEngineProvider)jsEngineProvider NS_DESIGNATED_INITIALIZER FB_OBJC_DIRECT;
 
 /**
  * This function initializes an RCTInstance if one does not yet exist.  This function is currently only called on the
diff --git a/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.mm b/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.mm
index 7826069b1a7838..e2f3e2a2c26a9c 100644
--- a/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.mm
+++ b/packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHost.mm
@@ -58,7 +58,7 @@ + (void)initialize
 - (instancetype)initWithHostDelegate:(id<RCTHostDelegate>)hostDelegate
           turboModuleManagerDelegate:(id<RCTTurboModuleManagerDelegate>)turboModuleManagerDelegate
                  bindingsInstallFunc:(facebook::react::ReactInstance::BindingsInstallFunc)bindingsInstallFunc
-                    jsEngineProvider:(nullable RCTHostJSEngineProvider)jsEngineProvider
+                    jsEngineProvider:(RCTHostJSEngineProvider)jsEngineProvider
 {
   if (self = [super init]) {
     _hostDelegate = hostDelegate;
@@ -149,14 +149,13 @@ - (void)preload
   }
   [self _refreshBundleURL];
   RCTReloadCommandSetBundleURL(_bundleURL);
-  _instance =
-      [[RCTInstance alloc] initWithDelegate:self
-                           jsEngineInstance:_jsEngineProvider ? _jsEngineProvider() : [_hostDelegate getJSEngine]
-                              bundleManager:_bundleManager
-                 turboModuleManagerDelegate:_turboModuleManagerDelegate
-                        onInitialBundleLoad:_onInitialBundleLoad
-                        bindingsInstallFunc:_bindingsInstallFunc
-                             moduleRegistry:_moduleRegistry];
+  _instance = [[RCTInstance alloc] initWithDelegate:self
+                                   jsEngineInstance:[self _provideJSEngine]
+                                      bundleManager:_bundleManager
+                         turboModuleManagerDelegate:_turboModuleManagerDelegate
+                                onInitialBundleLoad:_onInitialBundleLoad
+                                bindingsInstallFunc:_bindingsInstallFunc
+                                     moduleRegistry:_moduleRegistry];
 }
 
 - (RCTFabricSurface *)createSurfaceWithModuleName:(NSString *)moduleName
@@ -218,14 +217,13 @@ - (void)didReceiveReloadCommand
     _surfaceStartBuffer = [NSMutableArray arrayWithArray:[self _getAttachedSurfaces]];
   }
 
-  _instance =
-      [[RCTInstance alloc] initWithDelegate:self
-                           jsEngineInstance:_jsEngineProvider ? _jsEngineProvider() : [_hostDelegate getJSEngine]
-                              bundleManager:_bundleManager
-                 turboModuleManagerDelegate:_turboModuleManagerDelegate
-                        onInitialBundleLoad:_onInitialBundleLoad
-                        bindingsInstallFunc:_bindingsInstallFunc
-                             moduleRegistry:_moduleRegistry];
+  _instance = [[RCTInstance alloc] initWithDelegate:self
+                                   jsEngineInstance:[self _provideJSEngine]
+                                      bundleManager:_bundleManager
+                         turboModuleManagerDelegate:_turboModuleManagerDelegate
+                                onInitialBundleLoad:_onInitialBundleLoad
+                                bindingsInstallFunc:_bindingsInstallFunc
+                                     moduleRegistry:_moduleRegistry];
   [[NSNotificationCenter defaultCenter]
       postNotification:[NSNotification notificationWithName:RCTHostDidReloadNotification object:nil]];
 
@@ -278,6 +276,7 @@ - (void)registerSegmentWithId:(NSNumber *)segmentId path:(NSString *)path
 }
 
 #pragma mark - Private
+
 - (void)_refreshBundleURL FB_OBJC_DIRECT
 {
   // Reset the _bundleURL ivar if the RCTHost delegate presents a new bundleURL
@@ -308,4 +307,13 @@ - (void)_attachSurface:(RCTFabricSurface *)surface FB_OBJC_DIRECT
   return surfaces;
 }
 
+- (std::shared_ptr<facebook::react::JSEngineInstance>)_provideJSEngine
+{
+  RCTAssert(_jsEngineProvider, @"_jsEngineProvider must be non-nil");
+  std::shared_ptr<facebook::react::JSEngineInstance> jsEngine = _jsEngineProvider();
+  RCTAssert(jsEngine != nullptr, @"_jsEngineProvider must return a nonnull pointer");
+
+  return jsEngine;
+}
+
 @end