diff --git a/packages/mui-base/src/unstable_useModal/useModal.ts b/packages/mui-base/src/unstable_useModal/useModal.ts
index 1845810a01f7b2..4935fcf5f57e15 100644
--- a/packages/mui-base/src/unstable_useModal/useModal.ts
+++ b/packages/mui-base/src/unstable_useModal/useModal.ts
@@ -166,15 +166,15 @@ export function useModal(parameters: UseModalParameters): UseModalReturnValue {
   ): UseModalRootSlotProps<TOther> => {
     const propsEventHandlers = extractEventHandlers(parameters) as Partial<UseModalParameters>;
 
-    // The custom event handlers shouldn't be spread on the root element
-    delete propsEventHandlers.onTransitionEnter;
-    delete propsEventHandlers.onTransitionExited;
-
     const externalEventHandlers = {
       ...propsEventHandlers,
       ...otherHandlers,
     };
 
+    // The custom event handlers shouldn't be spread on the root element
+    delete externalEventHandlers.onTransitionEnter;
+    delete externalEventHandlers.onTransitionExited;
+
     return {
       role: 'presentation',
       ...externalEventHandlers,