How to Unlock a Mac Using the Apple Watch

Enabling Two-Factor Authentication

1. 
   Click the Apple menu on your Mac and select "System Preferences." You'll need Two-Factor Authentication enabled for your account in order to be able to unlock with your Apple Watch. You can enable it in the System Preferences menu.

   1. To set up Two-Factor on your iPhone instead, open the Settings app and select "iCloud." Tap your Apple ID and enter your password. Tap "Password & Security" and then tap "Set Up Two-Factor Authentication."^[1]
2. 
   Select "iCloud" and then click "Account Details." You'll be prompted to enter your Apple ID password.
3. 
   Click the "Security" tab. This will display the security settings for your Apple ID account.
4. 
   Click the "Set Up Two-Factor Authentication" button. This will start the Two-Factor setup process.

   1. If you have devices that aren't running iOS 9+ or OS X 10.11+, you'll be warned that those devices will require a special password in order to use them.
5. 
   Answer your security questions. You'll need to answer both questions before you can proceed.
6. 
   Enter a verification phone number. This phone number will be able to receive SMS codes in case you don't have access to your trusted devices when trying to log in.

   1. A valid credit card attached to your account can help you recover access if you get locked out when Two-Factor is activated. You can add one by logging into appleid.apple.com and adding your card in the "Payment Method" section.^[2]