diff --git a/packages/playwright/src/reporters/json.ts b/packages/playwright/src/reporters/json.ts
index b2fc664c15..ac33d25d9a 100644
--- a/packages/playwright/src/reporters/json.ts
+++ b/packages/playwright/src/reporters/json.ts
@@ -203,6 +203,7 @@ class JSONReporter implements ReporterV2 {
     const steps = result.steps.filter(s => s.category === 'test.step');
     const jsonResult: JSONReportTestResult = {
       workerIndex: result.workerIndex,
+      parallelIndex: result.parallelIndex,
       status: result.status,
       duration: result.duration,
       error: result.error,
diff --git a/packages/playwright/types/testReporter.d.ts b/packages/playwright/types/testReporter.d.ts
index 9662faee73..2abfa9592e 100644
--- a/packages/playwright/types/testReporter.d.ts
+++ b/packages/playwright/types/testReporter.d.ts
@@ -291,6 +291,7 @@ export interface JSONReportError {
 
 export interface JSONReportTestResult {
   workerIndex: number;
+  parallelIndex: number;
   status: TestStatus | undefined;
   duration: number;
   error: TestError | undefined;
diff --git a/tests/playwright-test/reporter-json.spec.ts b/tests/playwright-test/reporter-json.spec.ts
index f8ec8b9b0b..89b995ff35 100644
--- a/tests/playwright-test/reporter-json.spec.ts
+++ b/tests/playwright-test/reporter-json.spec.ts
@@ -327,3 +327,31 @@ test.describe('report location', () => {
     expect(fs.existsSync(testInfo.outputPath('foo', 'bar', 'baz', 'my-report.json'))).toBe(true);
   });
 });
+
+test('should report parallelIndex', async ({ runInlineTest }, testInfo) => {
+  const result = await runInlineTest({
+    'tests/a.spec.js': `
+      import { test, expect } from '@playwright/test';
+      const fs = require('fs');
+      test.describe.configure({ mode: 'parallel' });
+      test('test 1 passes!', async ({}) => {
+        await new Promise(f => setTimeout(f, 1000));
+      });
+      test('test 2 fails!', async ({}) => {
+        expect(1 + 1).toBe(3);
+        await new Promise(f => setTimeout(f, 1000));
+      });
+      test('test 3 passes!', async ({}) => {
+        await new Promise(f => setTimeout(f, 1000));
+      });
+    `
+  }, { 'workers': '2', 'reporter': 'json' });
+  expect(result.passed).toBe(2);
+  expect(result.failed).toBe(1);
+  expect(result.report.suites[0].specs[0].tests[0].results[0].workerIndex).toBe(0);
+  expect(result.report.suites[0].specs[1].tests[0].results[0].workerIndex).toBe(1);
+  expect(result.report.suites[0].specs[2].tests[0].results[0].workerIndex).toBe(2);
+  expect(result.report.suites[0].specs[0].tests[0].results[0].parallelIndex).toBe(0);
+  expect(result.report.suites[0].specs[1].tests[0].results[0].parallelIndex).toBe(1);
+  expect(result.report.suites[0].specs[2].tests[0].results[0].parallelIndex).toBe(1);
+});
diff --git a/utils/generate_types/overrides-testReporter.d.ts b/utils/generate_types/overrides-testReporter.d.ts
index b2e8f0e9e6..70365a911e 100644
--- a/utils/generate_types/overrides-testReporter.d.ts
+++ b/utils/generate_types/overrides-testReporter.d.ts
@@ -109,6 +109,7 @@ export interface JSONReportError {
 
 export interface JSONReportTestResult {
   workerIndex: number;
+  parallelIndex: number;
   status: TestStatus | undefined;
   duration: number;
   error: TestError | undefined;