diff --git a/integration_tests/__tests__/__snapshots__/show_config.test.js.snap b/integration_tests/__tests__/__snapshots__/show_config.test.js.snap
index 57e9f0d32837..b2ba413d57fb 100644
--- a/integration_tests/__tests__/__snapshots__/show_config.test.js.snap
+++ b/integration_tests/__tests__/__snapshots__/show_config.test.js.snap
@@ -75,7 +75,6 @@ exports[`--showConfig outputs config info and exits 1`] = `
     \\"testPathPattern\\": \\"\\",
     \\"testResultsProcessor\\": null,
     \\"updateSnapshot\\": \\"all\\",
-    \\"useStderr\\": false,
     \\"verbose\\": null,
     \\"watch\\": false,
     \\"watchman\\": true
diff --git a/integration_tests/__tests__/custom_reporters.test.js b/integration_tests/__tests__/custom_reporters.test.js
index a9fe577f55fd..e6785998b853 100644
--- a/integration_tests/__tests__/custom_reporters.test.js
+++ b/integration_tests/__tests__/custom_reporters.test.js
@@ -125,9 +125,8 @@ describe('Custom Reporters Integration', () => {
     ]);
 
     expect(status).toBe(0);
-    expect(stderr.trim()).toBe('');
-
     expect(stdout).toMatchSnapshot();
+    expect(stderr.trim()).toBe('');
   });
 
   test('prints reporter errors', () => {
diff --git a/integration_tests/__tests__/json_stdout.test.js b/integration_tests/__tests__/json_stdout.test.js
new file mode 100644
index 000000000000..6f397b14b545
--- /dev/null
+++ b/integration_tests/__tests__/json_stdout.test.js
@@ -0,0 +1,93 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+
+'use strict';
+
+const path = require('path');
+const os = require('os');
+const skipOnWindows = require('../../scripts/skip_on_windows');
+const {cleanup, writeFiles} = require('../utils');
+const runJest = require('../runJest');
+
+const DIR = path.resolve(os.tmpdir(), 'json_stdout_test');
+
+skipOnWindows.suite();
+
+beforeEach(() => cleanup(DIR));
+afterAll(() => cleanup(DIR));
+
+const reporterCode = `
+'use strict';
+
+console.log('at require time');
+console.log(console.log.toString());
+module.exports = class Reporter {
+  onRunStart() {
+    console.log('at runtime');
+  }
+};
+`;
+
+test('does not pollute stdout from third party code (or any code)', () => {
+  writeFiles(DIR, {
+    '.watchmanconfig': '',
+    '__tests__/hey.test.js': `test('test', () => {})`,
+    'custom_reporter.js': reporterCode,
+    'package.json': JSON.stringify({
+      jest: {
+        // Reporter will be required as a regular module in the master process
+        // before any of the test run, which makes it a perfect place to try
+        // to break the stdout by console.logging some text.
+        reporters: ['<rootDir>/custom_reporter.js', 'default'],
+      },
+    }),
+  });
+
+  let stdout;
+  let stderr;
+  ({stdout, stderr} = runJest(DIR, ['--json']));
+  expect(stdout).not.toMatch('at require time');
+  expect(stdout).not.toMatch('at runtime');
+  expect(stderr).toMatch('at require time');
+  expect(stderr).toMatch('at runtime');
+  expect(() => JSON.parse(stdout)).not.toThrow();
+
+  ({stdout, stderr} = runJest(DIR, ['--listTests', '__tests__/hey.test.js']));
+
+  expect(stdout).not.toMatch('at require time');
+  expect(stdout).not.toMatch('at runtime');
+  expect(stderr).not.toMatch('at require time');
+  expect(stderr).not.toMatch('at runtime');
+  expect(() => JSON.parse(stdout)).not.toThrow();
+  expect(stdout).toMatch('hey.test.js');
+});
+
+test('prints to stdout if not in json mode', () => {
+  writeFiles(DIR, {
+    '.watchmanconfig': '',
+    '__tests__/hey.test.js': `test('test', () => {})`,
+    'custom_reporter.js': reporterCode,
+    'package.json': JSON.stringify({
+      jest: {
+        // Reporter will be required as a regular module in the master process
+        // before any of the test run, which makes it a perfect place to try
+        // to break the stdout by console.logging some text.
+        reporters: ['<rootDir>/custom_reporter.js', 'default'],
+      },
+    }),
+  });
+
+  const {status, stdout, stderr} = runJest(DIR);
+  expect(stderr).not.toMatch('at runtime');
+  expect(stderr).not.toMatch('at require time');
+  expect(stdout).toMatch('at require time');
+  expect(stdout).toMatch('at runtime');
+  expect(status).toBe(0);
+});
diff --git a/packages/jest-cli/bin/jest.js b/packages/jest-cli/bin/jest.js
index 67ea4091b528..d8f1be52a727 100755
--- a/packages/jest-cli/bin/jest.js
+++ b/packages/jest-cli/bin/jest.js
@@ -11,4 +11,9 @@ if (process.env.NODE_ENV == null) {
   process.env.NODE_ENV = 'test';
 }
 
-require('../build/cli').run();
+const stdout = process.stdout;
+// Prevent any code from printing to stdout because it will break JSON
+// output if we run jest with `--json` or `--listTests` flags.
+Object.defineProperty(process, 'stdout', {value: process.stderr});
+
+require('../build/cli').run(undefined, undefined, stdout);
diff --git a/packages/jest-cli/src/__tests__/__snapshots__/watch_test_name_pattern_mode.test.js.snap b/packages/jest-cli/src/__tests__/__snapshots__/watch_test_name_pattern_mode.test.js.snap
index 73d0b2048b57..7c4a8b5da56b 100644
--- a/packages/jest-cli/src/__tests__/__snapshots__/watch_test_name_pattern_mode.test.js.snap
+++ b/packages/jest-cli/src/__tests__/__snapshots__/watch_test_name_pattern_mode.test.js.snap
@@ -20,7 +20,7 @@ exports[`Watch mode flows Pressing "T" enters pattern mode 1`] = `
 
  › should recognize null and undefined
 
- › should not output colors to pipe
+ › should not output colors to outputStream
 
  › should convert string to a RegExp
 
@@ -49,7 +49,7 @@ exports[`Watch mode flows Pressing "T" enters pattern mode 2`] = `
 
  › should recognize null and undefined
 
- › should not output colors to pipe
+ › should not output colors to outputStream
 
  › should convert string to a RegExp
 
@@ -187,7 +187,7 @@ exports[`Watch mode flows Results in pattern mode get truncated appropriately 1`
 
  › should recognize various types
 
- › should not output colors to pipe
+ › should not output colors to outputStream
 
  › should convert string to a RegExp
 
diff --git a/packages/jest-cli/src/__tests__/watch.test.js b/packages/jest-cli/src/__tests__/watch.test.js
index eaeaf1e658ca..f667ac240ac3 100644
--- a/packages/jest-cli/src/__tests__/watch.test.js
+++ b/packages/jest-cli/src/__tests__/watch.test.js
@@ -36,7 +36,7 @@ const watch = require('../watch');
 afterEach(runJestMock.mockReset);
 
 describe('Watch mode flows', () => {
-  let pipe;
+  let outputStream;
   let hasteMapInstances;
   let globalConfig;
   let contexts;
@@ -44,7 +44,7 @@ describe('Watch mode flows', () => {
 
   beforeEach(() => {
     const config = {roots: [], testPathIgnorePatterns: [], testRegex: ''};
-    pipe = {write: jest.fn()};
+    outputStream = {write: jest.fn()};
     globalConfig = {watch: true};
     hasteMapInstances = [{on: () => {}}];
     contexts = [{config}];
@@ -54,13 +54,19 @@ describe('Watch mode flows', () => {
   it('Correctly passing test path pattern', () => {
     globalConfig.testPathPattern = 'test-*';
 
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     expect(runJestMock.mock.calls[0][0]).toMatchObject({
       contexts,
       globalConfig,
       onComplete: expect.any(Function),
-      outputStream: pipe,
+      outputStream,
       testWatcher: new TestWatcher({isWatchMode: true}),
     });
   });
@@ -68,31 +74,49 @@ describe('Watch mode flows', () => {
   it('Correctly passing test name pattern', () => {
     globalConfig.testNamePattern = 'test-*';
 
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     expect(runJestMock.mock.calls[0][0]).toMatchObject({
       contexts,
       globalConfig,
       onComplete: expect.any(Function),
-      outputStream: pipe,
+      outputStream,
       testWatcher: new TestWatcher({isWatchMode: true}),
     });
   });
 
   it('Runs Jest once by default and shows usage', () => {
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
     expect(runJestMock.mock.calls[0][0]).toMatchObject({
       contexts,
       globalConfig,
       onComplete: expect.any(Function),
-      outputStream: pipe,
+      outputStream,
       testWatcher: new TestWatcher({isWatchMode: true}),
     });
-    expect(pipe.write.mock.calls.reverse()[0]).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.reverse()[0]).toMatchSnapshot();
   });
 
   it('Pressing "o" runs test in "only changed files" mode', () => {
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
     runJestMock.mockReset();
 
     stdin.emit(KEYS.O);
@@ -106,7 +130,13 @@ describe('Watch mode flows', () => {
   });
 
   it('Pressing "a" runs test in "watch all" mode', () => {
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
     runJestMock.mockReset();
 
     stdin.emit(KEYS.A);
@@ -120,14 +150,26 @@ describe('Watch mode flows', () => {
   });
 
   it('Pressing "ENTER" reruns the tests', () => {
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
     expect(runJestMock).toHaveBeenCalledTimes(1);
     stdin.emit(KEYS.ENTER);
     expect(runJestMock).toHaveBeenCalledTimes(2);
   });
 
   it('Pressing "u" reruns the tests in "update snapshot" mode', () => {
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
     runJestMock.mockReset();
 
     stdin.emit(KEYS.U);
diff --git a/packages/jest-cli/src/__tests__/watch_filename_pattern_mode.test.js b/packages/jest-cli/src/__tests__/watch_filename_pattern_mode.test.js
index 561840dbba14..1c65826a635a 100644
--- a/packages/jest-cli/src/__tests__/watch_filename_pattern_mode.test.js
+++ b/packages/jest-cli/src/__tests__/watch_filename_pattern_mode.test.js
@@ -4,8 +4,6 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @emails oncall+jsinfra
  */
 
 'use strict';
@@ -94,14 +92,14 @@ const globalConfig = {watch: true};
 afterEach(runJestMock.mockReset);
 
 describe('Watch mode flows', () => {
-  let pipe;
+  let outputStream;
   let hasteMapInstances;
   let contexts;
   let stdin;
 
   beforeEach(() => {
     terminalWidth = 80;
-    pipe = {write: jest.fn()};
+    outputStream = {write: jest.fn()};
     hasteMapInstances = [{on: () => {}}];
     contexts = [{config: {}}];
     stdin = new MockStdin();
@@ -109,16 +107,22 @@ describe('Watch mode flows', () => {
 
   it('Pressing "P" enters pattern mode', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     // Write a enter pattern mode
     stdin.emit(KEYS.P);
-    expect(pipe.write).toBeCalledWith(' pattern › ');
+    expect(outputStream.write).toBeCalledWith(' pattern › ');
 
     const assertPattern = hex => {
-      pipe.write.mockReset();
+      outputStream.write.mockReset();
       stdin.emit(hex);
-      expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+      expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
     };
 
     // Write a pattern
@@ -147,7 +151,13 @@ describe('Watch mode flows', () => {
     const toUnixPathPattern = pathPattern => pathPattern.replace(/\\\\/g, '/');
 
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     // Write a enter pattern mode
     stdin.emit(KEYS.P);
@@ -174,22 +184,34 @@ describe('Watch mode flows', () => {
 
   it('Results in pattern mode get truncated appropriately', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     stdin.emit(KEYS.P);
 
     [30, 25, 20].forEach(width => {
       terminalWidth = width;
       stdin.emit(KEYS.BACKSPACE);
-      pipe.write.mockReset();
+      outputStream.write.mockReset();
       stdin.emit(KEYS.A);
-      expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+      expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
     });
   });
 
   it('Shows the appropiate header when the filename filter is active', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     stdin.emit(KEYS.P);
 
@@ -198,20 +220,26 @@ describe('Watch mode flows', () => {
       .concat(KEYS.ENTER)
       .forEach(key => stdin.emit(key));
 
-    pipe.write.mockReset();
+    outputStream.write.mockReset();
     stdin.emit(KEYS.P);
-    expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
 
     ['p'].map(toHex).concat(KEYS.ENTER).forEach(key => stdin.emit(key));
 
-    pipe.write.mockReset();
+    outputStream.write.mockReset();
     stdin.emit(KEYS.P);
-    expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
   });
 
   it('Shows the appropiate header when the test name filter is active', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     stdin.emit(KEYS.T);
 
@@ -220,20 +248,26 @@ describe('Watch mode flows', () => {
       .concat(KEYS.ENTER)
       .forEach(key => stdin.emit(key));
 
-    pipe.write.mockReset();
+    outputStream.write.mockReset();
     stdin.emit(KEYS.T);
-    expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
 
     ['t'].map(toHex).concat(KEYS.ENTER).forEach(key => stdin.emit(key));
 
-    pipe.write.mockReset();
+    outputStream.write.mockReset();
     stdin.emit(KEYS.T);
-    expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
   });
 
   it('Shows the appropiate header when both filters are active', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     stdin.emit(KEYS.P);
 
@@ -248,14 +282,20 @@ describe('Watch mode flows', () => {
       .concat(KEYS.ENTER)
       .forEach(key => stdin.emit(key));
 
-    pipe.write.mockReset();
+    outputStream.write.mockReset();
     stdin.emit(KEYS.T);
-    expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
   });
 
   it('Pressing "c" clears the filters', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     stdin.emit(KEYS.P);
 
@@ -272,9 +312,9 @@ describe('Watch mode flows', () => {
 
     stdin.emit(KEYS.C);
 
-    pipe.write.mockReset();
+    outputStream.write.mockReset();
     stdin.emit(KEYS.P);
-    expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+    expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
   });
 });
 
diff --git a/packages/jest-cli/src/__tests__/watch_test_name_pattern_mode.test.js b/packages/jest-cli/src/__tests__/watch_test_name_pattern_mode.test.js
index 66691a48ec1e..eda61e204a7e 100644
--- a/packages/jest-cli/src/__tests__/watch_test_name_pattern_mode.test.js
+++ b/packages/jest-cli/src/__tests__/watch_test_name_pattern_mode.test.js
@@ -75,7 +75,7 @@ jest.doMock(
             testResults: [{title: 'should recognize null and undefined'}],
           },
           {
-            testResults: [{title: 'should not output colors to pipe'}],
+            testResults: [{title: 'should not output colors to outputStream'}],
           },
           {
             testResults: [{title: 'should convert string to a RegExp'}],
@@ -110,14 +110,14 @@ const globalConfig = {
 afterEach(runJestMock.mockReset);
 
 describe('Watch mode flows', () => {
-  let pipe;
+  let outputStream;
   let hasteMapInstances;
   let contexts;
   let stdin;
 
   beforeEach(() => {
     terminalWidth = 80;
-    pipe = {write: jest.fn()};
+    outputStream = {write: jest.fn()};
     hasteMapInstances = [{on: () => {}}];
     contexts = [{config: {}}];
     stdin = new MockStdin();
@@ -125,16 +125,22 @@ describe('Watch mode flows', () => {
 
   it('Pressing "T" enters pattern mode', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     // Write a enter pattern mode
     stdin.emit(KEYS.T);
-    expect(pipe.write).toBeCalledWith(' pattern › ');
+    expect(outputStream.write).toBeCalledWith(' pattern › ');
 
     const assertPattern = hex => {
-      pipe.write.mockReset();
+      outputStream.write.mockReset();
       stdin.emit(hex);
-      expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+      expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
     };
 
     // Write a pattern
@@ -160,7 +166,13 @@ describe('Watch mode flows', () => {
 
   it('can select a specific test name from the typeahead results', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     // Write a enter pattern mode
     stdin.emit(KEYS.T);
@@ -185,16 +197,22 @@ describe('Watch mode flows', () => {
 
   it('Results in pattern mode get truncated appropriately', () => {
     contexts[0].config = {rootDir: ''};
-    watch(globalConfig, contexts, pipe, hasteMapInstances, stdin);
+    watch({
+      contexts,
+      globalConfig,
+      hasteMapInstances,
+      outputStream,
+      stdin,
+    });
 
     stdin.emit(KEYS.T);
 
     [50, 30].forEach(width => {
       terminalWidth = width;
       stdin.emit(KEYS.BACKSPACE);
-      pipe.write.mockReset();
+      outputStream.write.mockReset();
       stdin.emit(KEYS.T);
-      expect(pipe.write.mock.calls.join('\n')).toMatchSnapshot();
+      expect(outputStream.write.mock.calls.join('\n')).toMatchSnapshot();
     });
   });
 });
diff --git a/packages/jest-cli/src/cli/index.js b/packages/jest-cli/src/cli/index.js
index 3456d839eb5c..a91342924050 100644
--- a/packages/jest-cli/src/cli/index.js
+++ b/packages/jest-cli/src/cli/index.js
@@ -18,6 +18,7 @@ import {
   createDirectory,
   validateCLIOptions,
 } from 'jest-util';
+import {Console as NativeConsole} from 'console';
 import {readConfig} from 'jest-config';
 import {version as VERSION} from '../../package.json';
 import args from './args';
@@ -34,45 +35,53 @@ import TestWatcher from '../test_watcher';
 import watch from '../watch';
 import yargs from 'yargs';
 
-async function run(maybeArgv?: Argv, project?: Path) {
+async function run(
+  maybeArgv?: Argv,
+  project?: Path,
+  stdout?: stream$Writable | tty$WriteStream,
+) {
   const argv: Argv = _buildArgv(maybeArgv, project);
   const projects = _getProjectListFromCLIArgs(argv, project);
   // If we're running a single Jest project, we might want to use another
   // version of Jest (the one that is specified in this project's package.json)
   const runCLIFn = _getRunCLIFn(projects);
 
-  const {results, globalConfig} = await runCLIFn(argv, projects);
+  const {results, globalConfig} = await runCLIFn(argv, projects, stdout);
   _readResultsAndExit(results, globalConfig);
 }
 
 const runCLI = async (
   argv: Argv,
   projects: Array<Path>,
+  stdout?: stream$Writable | tty$WriteStream = process.stdout,
 ): Promise<{results: AggregatedResult, globalConfig: GlobalConfig}> => {
   let results;
   // Optimize 'fs' module and make it more compatible with multiple platforms.
   _patchGlobalFSModule();
 
-  // If we output a JSON object, we can't write anything to stdout, since
-  // it'll break the JSON structure and it won't be valid.
-  const outputStream =
-    argv.json || argv.useStderr ? process.stderr : process.stdout;
-
-  argv.version && _printVersionAndExit(outputStream);
+  argv.version && _printVersionAndExit(stdout);
 
   try {
     const {globalConfig, configs, hasDeprecationWarnings} = _getConfigs(
       projects,
       argv,
-      outputStream,
+      stdout,
     );
 
+    _restoreStdoutIfNeeded(globalConfig, stdout);
+
+    // If we output a JSON object, we can't write anything to stdout, since
+    // it'll break the JSON structure and it won't be valid.
+    const outputStream =
+      argv.json || argv.useStderr ? process.stderr : process.stdout;
+
     await _run(
       globalConfig,
       configs,
       hasDeprecationWarnings,
       outputStream,
       (r: AggregatedResult) => (results = r),
+      stdout,
     );
 
     if (argv.watch || argv.watchAll) {
@@ -98,6 +107,24 @@ const runCLI = async (
   }
 };
 
+// We hijack `process.stdout` and redirect everything to `process.stderr`
+// very early in the Jest process to prevent any of required code to pollute
+// stdout with any `console.log`s (this will break JSON output in stdout). If
+// we aren't planning to output JSON (or --useStderr) we will reassign
+// stdout back to its original value here.
+const _restoreStdoutIfNeeded = (globalConfig: GlobalConfig, stdout) => {
+  if (
+    !globalConfig.json &&
+    !globalConfig.listTests &&
+    !globalConfig.useStderr
+  ) {
+    Object.defineProperty(process, 'stdout', {value: stdout});
+    Object.defineProperty(global, 'console', {
+      value: new NativeConsole(process.stdout, process.stderr),
+    });
+  }
+};
+
 const _readResultsAndExit = (
   result: ?AggregatedResult,
   globalConfig: GlobalConfig,
@@ -144,10 +171,10 @@ const _printDebugInfoAndExitIfNeeded = (
   argv,
   globalConfig,
   configs,
-  outputStream,
+  stdout,
 ) => {
   if (argv.debug || argv.showConfig) {
-    logDebugMessages(globalConfig, configs, outputStream);
+    logDebugMessages(globalConfig, configs, stdout);
   }
   if (argv.showConfig) {
     process.exit(0);
@@ -194,7 +221,7 @@ const _ensureNoDuplicateConfigs = (parsedConfigs, projects) => {
 const _getConfigs = (
   projectsFromCLIArgs: Array<Path>,
   argv: Argv,
-  outputStream,
+  stdout,
 ): {
   globalConfig: GlobalConfig,
   configs: Array<ProjectConfig>,
@@ -243,7 +270,7 @@ const _getConfigs = (
     throw new Error('jest: No configuration found for any project.');
   }
 
-  _printDebugInfoAndExitIfNeeded(argv, globalConfig, configs, outputStream);
+  _printDebugInfoAndExitIfNeeded(argv, globalConfig, configs, stdout);
 
   return {
     configs,
@@ -288,6 +315,7 @@ const _run = async (
   hasDeprecationWarnings,
   outputStream,
   onComplete,
+  stdout,
 ) => {
   // Queries to hg/git can take a while, so we need to start the process
   // as soon as possible, so by the time we need the result it's already there.
@@ -307,6 +335,7 @@ const _run = async (
         outputStream,
         hasteMapInstances,
         changedFilesPromise,
+        stdout,
       )
     : await _runWithoutWatch(
         globalConfig,
@@ -314,6 +343,7 @@ const _run = async (
         outputStream,
         onComplete,
         changedFilesPromise,
+        stdout,
       );
 };
 
@@ -325,17 +355,30 @@ const _runWatch = async (
   outputStream,
   hasteMapInstances,
   changedFilesPromise,
+  stdout,
 ) => {
   if (hasDeprecationWarnings) {
     try {
       await handleDeprecationWarnings(outputStream, process.stdin);
-      return watch(globalConfig, contexts, outputStream, hasteMapInstances);
+      return watch({
+        contexts,
+        globalConfig,
+        hasteMapInstances,
+        outputStream,
+        stdout,
+      });
     } catch (e) {
       process.exit(0);
     }
   }
 
-  return watch(globalConfig, contexts, outputStream, hasteMapInstances);
+  return watch({
+    contexts,
+    globalConfig,
+    hasteMapInstances,
+    outputStream,
+    stdout,
+  });
 };
 
 const _runWithoutWatch = async (
@@ -344,6 +387,7 @@ const _runWithoutWatch = async (
   outputStream,
   onComplete,
   changedFilesPromise,
+  stdout,
 ) => {
   const startRun = async () => {
     if (!globalConfig.listTests) {
@@ -356,6 +400,7 @@ const _runWithoutWatch = async (
       onComplete,
       outputStream,
       startRun,
+      stdout,
       testWatcher: new TestWatcher({isWatchMode: false}),
     });
   };
diff --git a/packages/jest-cli/src/reporters/default_reporter.js b/packages/jest-cli/src/reporters/default_reporter.js
index 2dca4d492c4a..154f2e88a1e7 100644
--- a/packages/jest-cli/src/reporters/default_reporter.js
+++ b/packages/jest-cli/src/reporters/default_reporter.js
@@ -8,8 +8,6 @@
  * @flow
  */
 
-/* global stream$Writable, tty$WriteStream */
-
 import type {AggregatedResult, TestResult} from 'types/TestResult';
 import type {GlobalConfig, Path, ProjectConfig} from 'types/Config';
 import type {Test} from 'types/TestRunner';
diff --git a/packages/jest-cli/src/run_jest.js b/packages/jest-cli/src/run_jest.js
index 85d1dcf9c066..1bcf54c11bb1 100644
--- a/packages/jest-cli/src/run_jest.js
+++ b/packages/jest-cli/src/run_jest.js
@@ -121,12 +121,12 @@ const processResults = (runResults, options) => {
       const filePath = path.resolve(process.cwd(), outputFile);
 
       fs.writeFileSync(filePath, JSON.stringify(formatTestResults(runResults)));
-      process.stdout.write(
+      options.stdout.write(
         `Test results written to: ` +
           `${path.relative(process.cwd(), filePath)}\n`,
       );
     } else {
-      process.stdout.write(JSON.stringify(formatTestResults(runResults)));
+      options.stdout.write(JSON.stringify(formatTestResults(runResults)));
     }
   }
   return options.onComplete && options.onComplete(runResults);
@@ -140,6 +140,7 @@ const runJest = async ({
   startRun,
   changedFilesPromise,
   onComplete,
+  stdout,
 }: {
   globalConfig: GlobalConfig,
   contexts: Array<Context>,
@@ -148,6 +149,7 @@ const runJest = async ({
   startRun: (globalConfig: GlobalConfig) => *,
   changedFilesPromise: ?ChangedFilesPromise,
   onComplete: (testResults: AggregatedResult) => any,
+  stdout: stream$Writable | tty$WriteStream,
 }) => {
   const sequencer = new TestSequencer();
   let allTests = [];
@@ -167,7 +169,7 @@ const runJest = async ({
   allTests = sequencer.sort(allTests);
 
   if (globalConfig.listTests) {
-    console.log(JSON.stringify(allTests.map(test => test.path)));
+    stdout.write(JSON.stringify(allTests.map(test => test.path)));
     onComplete && onComplete(makeEmptyAggregatedTestResult());
     return null;
   }
@@ -202,6 +204,7 @@ const runJest = async ({
     isJSON: globalConfig.json,
     onComplete,
     outputFile: globalConfig.outputFile,
+    stdout,
     testResultsProcessor: globalConfig.testResultsProcessor,
   });
 };
diff --git a/packages/jest-cli/src/watch.js b/packages/jest-cli/src/watch.js
index e1e7785b298d..719ff4ac3de4 100644
--- a/packages/jest-cli/src/watch.js
+++ b/packages/jest-cli/src/watch.js
@@ -32,17 +32,28 @@ import {KEYS, CLEAR} from './constants';
 const isInteractive = process.stdout.isTTY && !isCI;
 let hasExitListener = false;
 
-const watch = (
-  initialGlobalConfig: GlobalConfig,
+const watch = ({
+  globalConfig: initialGlobalConfig,
+  contexts,
+  outputStream,
+  hasteMapInstances,
+  stdin,
+  stdout,
+}: {
+  globalConfig: GlobalConfig,
   contexts: Array<Context>,
   outputStream: stream$Writable | tty$WriteStream,
   hasteMapInstances: Array<HasteMap>,
-  stdin?: stream$Readable | tty$ReadStream = process.stdin,
-) => {
+  stdin?: stream$Readable | tty$ReadStream,
+  stdout: stream$Writable | tty$WriteStream,
+}) => {
   // `globalConfig` will be consantly updated and reassigned as a result of
   // watch mode interactions.
   let globalConfig = initialGlobalConfig;
 
+  if (!stdin) {
+    stdin = process.stdin;
+  }
   globalConfig = updateGlobalConfig(globalConfig, {
     mode: globalConfig.watch ? 'watch' : 'watchAll',
   });
@@ -134,6 +145,7 @@ const watch = (
       },
       outputStream,
       startRun,
+      stdout,
       testWatcher,
     }).catch(error => console.error(chalk.red(error.stack)));
   };
diff --git a/packages/jest-config/src/defaults.js b/packages/jest-config/src/defaults.js
index a6814b4995c8..6e27240bbfec 100644
--- a/packages/jest-config/src/defaults.js
+++ b/packages/jest-config/src/defaults.js
@@ -62,7 +62,6 @@ module.exports = ({
   testURL: 'about:blank',
   timers: 'real',
   transformIgnorePatterns: [NODE_MODULES_REGEXP],
-  useStderr: false,
   verbose: null,
   watch: false,
   watchman: true,
diff --git a/types/Config.js b/types/Config.js
index e3f38882ef80..f8a49cef6925 100644
--- a/types/Config.js
+++ b/types/Config.js
@@ -54,7 +54,6 @@ export type DefaultOptions = {|
   testURL: string,
   timers: 'real' | 'fake',
   transformIgnorePatterns: Array<Glob>,
-  useStderr: boolean,
   verbose: ?boolean,
   watch: boolean,
   watchman: boolean,