diff --git a/packages/js/src/plugins/rollup/type-definitions.spec.ts b/packages/js/src/plugins/rollup/type-definitions.spec.ts
new file mode 100644
index 00000000000000..0fcb6889b68d9b
--- /dev/null
+++ b/packages/js/src/plugins/rollup/type-definitions.spec.ts
@@ -0,0 +1,62 @@
+import { typeDefinitions } from './type-definitions';
+describe('typeDefinitions', () => {
+  it('should emit correct .d.ts filenames for various file formats', () => {
+    const mockBundle = {
+      'index.js': {
+        type: 'chunk',
+        isEntry: true,
+        fileName: 'index.js',
+        facadeModuleId: '/project/src/index.ts',
+        exports: ['default', 'namedExport1', 'namedExport2'],
+      },
+      'index1.js': {
+        type: 'chunk',
+        isEntry: true,
+        fileName: 'index.cjs',
+        facadeModuleId: '/project/src/index.ts',
+        exports: ['default', 'namedExport1', 'namedExport2'],
+      },
+      'index2.js': {
+        type: 'chunk',
+        isEntry: true,
+        fileName: 'index.mjs',
+        facadeModuleId: '/project/src/index.ts',
+        exports: ['default', 'namedExport1', 'namedExport2'],
+      },
+      'index3.js': {
+        type: 'chunk',
+        isEntry: true,
+        fileName: 'index.cjs.js',
+        facadeModuleId: '/project/src/index.ts',
+        exports: ['default', 'namedExport1', 'namedExport2'],
+      },
+      'index4.js': {
+        type: 'chunk',
+        isEntry: true,
+        fileName: 'index.mjs.js',
+        facadeModuleId: '/project/src/index.ts',
+        exports: ['default', 'namedExport1', 'namedExport2'],
+      },
+    };
+
+    const mockOpts = {}; // Can be left empty for this scenario
+
+    const mockEmitFile = jest.fn();
+
+    const plugin = typeDefinitions({ projectRoot: '/project' });
+
+    // Simulate the `this` context of a Rollup plugin
+    const mockContext = {
+      emitFile: mockEmitFile,
+    };
+
+    // Run the plugin's `generateBundle` function
+    (async function testPlugin() {
+      await plugin.generateBundle.call(mockContext, mockOpts, mockBundle);
+
+      mockEmitFile.mock.calls.forEach(([{ fileName }]) => {
+        expect(fileName).toBe('index.d.ts');
+      });
+    })();
+  });
+});
diff --git a/packages/js/src/plugins/rollup/type-definitions.ts b/packages/js/src/plugins/rollup/type-definitions.ts
index f82ddf505bab5d..33cf9811c72242 100644
--- a/packages/js/src/plugins/rollup/type-definitions.ts
+++ b/packages/js/src/plugins/rollup/type-definitions.ts
@@ -38,7 +38,13 @@ export function typeDefinitions(options: { projectRoot: string }) {
           /\.[cm]?[jt]sx?$/,
           ''
         );
-        const dtsFileName = file.fileName.replace(/\.[cm]?js$/, '.d.ts');
+
+        // Replace various JavaScript file extensions (e.g., .js, .cjs, .mjs, .cjs.js, .mjs.js) with .d.ts for generating type definition file names.
+        const dtsFileName = file.fileName.replace(
+          /(\.cjs|\.mjs|\.js|\.cjs\.js|\.mjs\.js)$/,
+          '.d.ts'
+        );
+
         const relativeSourceDtsName = JSON.stringify('./' + entrySourceDtsName);
         const dtsFileSource = hasDefaultExport
           ? stripIndents`