diff --git a/packages/react-native/Libraries/Blob/URL.js b/packages/react-native/Libraries/Blob/URL.js
index f4f879a51214..236e3ce5a666 100644
--- a/packages/react-native/Libraries/Blob/URL.js
+++ b/packages/react-native/Libraries/Blob/URL.js
@@ -85,7 +85,7 @@ export class URL {
         const split = this._url.split('#');
         const beforeHash = split[0];
         const website = beforeHash.split('://')[1];
-        if (!website.includes('/')) {
+        if (website != null && !website.includes('/')) {
           this._url = split.join('/#');
         }
       }
diff --git a/packages/react-native/Libraries/Blob/__tests__/URL-test.js b/packages/react-native/Libraries/Blob/__tests__/URL-test.js
index 72467dc08ebb..cc597a1e780a 100644
--- a/packages/react-native/Libraries/Blob/__tests__/URL-test.js
+++ b/packages/react-native/Libraries/Blob/__tests__/URL-test.js
@@ -168,4 +168,9 @@ describe('URL', function () {
       'https://example.com/path/to/resource',
     );
   });
+
+  it('should handle URLs with hash but no protocol separator', () => {
+    // URL with hash but no "://" should not crash
+    expect(() => new URL('mailto:user@example.com#section')).not.toThrow();
+  });
 });