diff --git a/doc/api/child_process.md b/doc/api/child_process.md
index 8d3186cbc4090d..ee8f0b4f0bc939 100644
--- a/doc/api/child_process.md
+++ b/doc/api/child_process.md
@@ -1253,9 +1253,11 @@ does not indicate that the child process has been terminated.
 added: v0.1.90
 -->
 
-* {integer}
+* {integer|undefined}
 
-Returns the process identifier (PID) of the child process.
+Returns the process identifier (PID) of the child process. If the child process
+fails to spawn due to errors, then the value is `undefined` and `error` is
+emitted.
 
 ```js
 const { spawn } = require('child_process');
diff --git a/test/parallel/test-child-process-cwd.js b/test/parallel/test-child-process-cwd.js
index fb782234539db4..232f1d0f3d5316 100644
--- a/test/parallel/test-child-process-cwd.js
+++ b/test/parallel/test-child-process-cwd.js
@@ -28,11 +28,14 @@ const assert = require('assert');
 const { spawn } = require('child_process');
 
 // Spawns 'pwd' with given options, then test
+// - whether the child pid is undefined or number,
 // - whether the exit code equals expectCode,
 // - optionally whether the trimmed stdout result matches expectData
-function testCwd(options, expectCode = 0, expectData) {
+function testCwd(options, expectPidType, expectCode = 0, expectData) {
   const child = spawn(...common.pwdCommand, options);
 
+  assert.strictEqual(typeof child.pid, expectPidType);
+
   child.stdout.setEncoding('utf8');
 
   // No need to assert callback since `data` is asserted.
@@ -57,18 +60,18 @@ function testCwd(options, expectCode = 0, expectData) {
 
 // Assume does-not-exist doesn't exist, expect exitCode=-1 and errno=ENOENT
 {
-  testCwd({ cwd: 'does-not-exist' }, -1)
+  testCwd({ cwd: 'does-not-exist' }, 'undefined', -1)
     .on('error', common.mustCall(function(e) {
       assert.strictEqual(e.code, 'ENOENT');
     }));
 }
 
 // Assume these exist, and 'pwd' gives us the right directory back
-testCwd({ cwd: tmpdir.path }, 0, tmpdir.path);
+testCwd({ cwd: tmpdir.path }, 'number', 0, tmpdir.path);
 const shouldExistDir = common.isWindows ? process.env.windir : '/dev';
-testCwd({ cwd: shouldExistDir }, 0, shouldExistDir);
+testCwd({ cwd: shouldExistDir }, 'number', 0, shouldExistDir);
 
 // Spawn() shouldn't try to chdir() to invalid arg, so this should just work
-testCwd({ cwd: '' });
-testCwd({ cwd: undefined });
-testCwd({ cwd: null });
+testCwd({ cwd: '' }, 'number');
+testCwd({ cwd: undefined }, 'number');
+testCwd({ cwd: null }, 'number');
diff --git a/test/parallel/test-child-process-exec-error.js b/test/parallel/test-child-process-exec-error.js
index eaddeb6614e921..cd45f3071c2920 100644
--- a/test/parallel/test-child-process-exec-error.js
+++ b/test/parallel/test-child-process-exec-error.js
@@ -24,17 +24,21 @@ const common = require('../common');
 const assert = require('assert');
 const child_process = require('child_process');
 
-function test(fn, code) {
-  fn('does-not-exist', common.mustCall(function(err) {
+function test(fn, code, expectPidType = 'number') {
+  const child = fn('does-not-exist', common.mustCall(function(err) {
     assert.strictEqual(err.code, code);
     assert(err.cmd.includes('does-not-exist'));
   }));
+
+  assert.strictEqual(typeof child.pid, expectPidType);
 }
 
+// With `shell: true`, expect pid (of the shell)
 if (common.isWindows) {
-  test(child_process.exec, 1); // Exit code of cmd.exe
+  test(child_process.exec, 1, 'number'); // Exit code of cmd.exe
 } else {
-  test(child_process.exec, 127); // Exit code of /bin/sh
+  test(child_process.exec, 127, 'number'); // Exit code of /bin/sh
 }
 
-test(child_process.execFile, 'ENOENT');
+// With `shell: false`, expect no pid
+test(child_process.execFile, 'ENOENT', 'undefined');
diff --git a/test/parallel/test-child-process-spawn-error.js b/test/parallel/test-child-process-spawn-error.js
index a3464a505d4f7c..ed1c8fac9f97ed 100644
--- a/test/parallel/test-child-process-spawn-error.js
+++ b/test/parallel/test-child-process-spawn-error.js
@@ -41,6 +41,9 @@ assert.strictEqual(enoentChild.stdio[0], enoentChild.stdin);
 assert.strictEqual(enoentChild.stdio[1], enoentChild.stdout);
 assert.strictEqual(enoentChild.stdio[2], enoentChild.stderr);
 
+// Verify pid is not assigned.
+assert.strictEqual(enoentChild.pid, undefined);
+
 enoentChild.on('spawn', common.mustNotCall());
 
 enoentChild.on('error', common.mustCall(function(err) {