diff --git a/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.spec.ts b/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.spec.ts
index 6332c562c8005..414bac03030dd 100644
--- a/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.spec.ts
+++ b/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.spec.ts
@@ -159,4 +159,112 @@ describe('buildEsbuildOptions', () => {
       },
     });
   });
+
+  it('should respect user defined outExtension', () => {
+    expect(
+      buildEsbuildOptions(
+        'esm',
+        {
+          platform: 'node',
+          main: 'apps/myapp/src/index.ts',
+          outputPath: 'dist/apps/myapp',
+          tsConfig: 'apps/myapp/tsconfig.app.json',
+          project: 'apps/myapp/package.json',
+          outputFileName: 'index.js',
+          assets: [],
+          singleEntry: true,
+          external: [],
+          esbuildOptions: {
+            outExtension: {
+              '.js': '.mjs',
+            },
+          },
+        },
+        context
+      )
+    ).toEqual({
+      bundle: true,
+      entryNames: '[dir]/[name]',
+      entryPoints: ['apps/myapp/src/index.ts'],
+      format: 'esm',
+      platform: 'node',
+      outfile: 'dist/apps/myapp/index.mjs',
+      tsconfig: 'apps/myapp/tsconfig.app.json',
+      external: [],
+      outExtension: {
+        '.js': '.mjs',
+      },
+    });
+
+    expect(
+      buildEsbuildOptions(
+        'cjs',
+        {
+          platform: 'node',
+          main: 'apps/myapp/src/index.ts',
+          outputPath: 'dist/apps/myapp',
+          tsConfig: 'apps/myapp/tsconfig.app.json',
+          project: 'apps/myapp/package.json',
+          outputFileName: 'index.js',
+          assets: [],
+          singleEntry: true,
+          external: [],
+          esbuildOptions: {
+            outExtension: {
+              '.js': '.js',
+            },
+          },
+        },
+        context
+      )
+    ).toEqual({
+      bundle: true,
+      entryNames: '[dir]/[name]',
+      entryPoints: ['apps/myapp/src/index.ts'],
+      format: 'cjs',
+      platform: 'node',
+      outfile: 'dist/apps/myapp/index.js',
+      tsconfig: 'apps/myapp/tsconfig.app.json',
+      external: [],
+      outExtension: {
+        '.js': '.js',
+      },
+    });
+
+    // ESM cannot be mapped to .cjs so ignore
+    expect(
+      buildEsbuildOptions(
+        'esm',
+        {
+          platform: 'node',
+          main: 'apps/myapp/src/index.ts',
+          outputPath: 'dist/apps/myapp',
+          tsConfig: 'apps/myapp/tsconfig.app.json',
+          project: 'apps/myapp/package.json',
+          outputFileName: 'index.js',
+          assets: [],
+          singleEntry: true,
+          external: [],
+          esbuildOptions: {
+            outExtension: {
+              '.js': '.cjs',
+            },
+          },
+        },
+        context
+      )
+    ).toEqual({
+      bundle: true,
+      entryNames: '[dir]/[name]',
+      entryPoints: ['apps/myapp/src/index.ts'],
+      format: 'esm',
+      platform: 'node',
+      outfile: 'dist/apps/myapp/index.js',
+      tsconfig: 'apps/myapp/tsconfig.app.json',
+      external: [],
+      outExtension: {
+        '.js': '.js',
+      },
+    });
+  });
 });
diff --git a/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.ts b/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.ts
index 3a9b96623af5c..441f945c97f0c 100644
--- a/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.ts
+++ b/packages/esbuild/src/executors/esbuild/lib/build-esbuild-options.ts
@@ -31,7 +31,9 @@ export function buildEsbuildOptions(
     metafile: options.metafile,
     tsconfig: options.tsConfig,
     format,
-    outExtension: { '.js': getOutExtension(format) },
+    outExtension: {
+      '.js': getOutExtension(format, options),
+    },
   };
 
   if (options.platform === 'browser') {
@@ -47,8 +49,21 @@ export function buildEsbuildOptions(
   return esbuildOptions;
 }
 
-function getOutExtension(format: 'cjs' | 'esm') {
-  return format === 'esm' ? ESM_FILE_EXTENSION : CJS_FILE_EXTENSION;
+function getOutExtension(
+  format: 'cjs' | 'esm',
+  options: EsBuildExecutorOptions
+): string {
+  const userDefinedExt = options.esbuildOptions?.outExtension?.['.js'];
+  // Allow users to change the output extensions from default CJS and ESM extensions.
+  // CJS -> .js
+  // ESM -> .mjs
+  return userDefinedExt === '.js' && format === 'cjs'
+    ? '.js'
+    : userDefinedExt === '.mjs' && format === 'esm'
+    ? '.mjs'
+    : format === 'esm'
+    ? ESM_FILE_EXTENSION
+    : CJS_FILE_EXTENSION;
 }
 
 function getOutfile(
@@ -56,11 +71,11 @@ function getOutfile(
   options: EsBuildExecutorOptions,
   context: ExecutorContext
 ) {
+  const ext = getOutExtension(format, options);
   const candidate = joinPathFragments(
     context.target.options.outputPath,
     options.outputFileName
   );
-  const ext = getOutExtension(format);
   const { dir, name } = parse(candidate);
   return `${dir}/${name}${ext}`;
 }