Fed up of having to enter your password to unlock your Mac? It's probably not high on your list of time-wasters, but if you'd like to add another level of security to a work Mac (perhaps all your colleagues know your password), or if you'd just like to do it to show off your geeky skillz it's a useful feature.

Here's how to set it up so your Apple Watch can unlock your Mac.

What do I need in order to unlock my Mac with my Apple Watch?

First things first: You’ll need to be running macOS Sierra on your Mac. Here’s how to install macOS Sierra) if you haven’t done so already. 

You will also need to update your Watch to watchOS 3 (here’s how to do that: How to install watchOS on your Apple Watch).

Step 1: Set up Two-Factor Authentication on your Mac

Before you can use your Apple Watch to unlock your Mac you’ll need to set up Two-Factor Authentication on your Mac or your iOS device. We explain how to set up two-factor authentication in this article: How to set up two-factor authentication.

Two-Factor Authentication adds an extra level of security - in addition to using your password Apple will send you by text message, or via an alert on you Mac screen, a numerical code that you will be required to use.

This is different to two-step verification and if you have that set up on your Mac you will need to disable it. (We have a comparison between two-step and two-factor verification here.)

To set up Two-Factor Authentication on your Mac, go to System Preferences > iCloud > Account Details. Log in using your Apple ID. Then select Security and Turn On Two-Factor Authentication.

Next you will be asked for a phone number that Apple can text a number too. When you receive the text from Apple add that number to the verification screen on your Mac.

You can also set up two factor authentication on your iPad or iPhone. Go to Settings > iCloud and tap your Apple ID. Then choose Password & Security > Turn on Two-Factor Authentication.

Beware that once you have set up two-factor authentication it becomes a lot more difficult to sign into Apple devices running older versions of OS X or iOS - so much more difficult that you may decide that the hassle of this outweighs the hassle of logging onto your Mac the old fashioned way…

If like us you own an older Apple TV (one that doesn't have the App Store) you may fall into the trap of locking yourself out because you don't realise that you need to ender a code after your password. (On older devices you will have to add a six-digit verification code at end of your password). This code will be sent to a ‘trusted device’ running iOS 9 and later or OS X El Capitan and later, or it will be sent to your phone number.

Step 2: Set up a passcode on your Apple Watch

Next you will need to set up a passcode on your Apple Watch using the Watch app on your iPhone if you haven’t done so already.

Open the Watch app on your iPhone by tapping the Watch icon. Go to My Watch > Passcode and then tap Turn Passcode On.

Add a passcode here - it’s advised that you use a different passcode to the one you use with your iPhone.

Step 3: Disable automatic log in to your Mac

The next step is to disable automatic log in on your Mac, if it is set to log on automatically during start up.

To do so, go to System Preferences > Security & Privacy, and under the General tab uncheck Disable Automatic Login.

If you have FileVault turned on you won’t have the Disable Automatic Login option because with FileVault manual login is required for all accounts.

Step 4: Allow your Apple Watch to unlock your Mac

In System Preferences go to Security & Privacy and check the Allow your Apple Watch to unlock your Mac box.

If you don’t see this option there could be a number of reasons. Your Mac needs to be no older than 2013, you need to be running watchOS 3 on your Watch, and you can’t be running two-step verification (it has to be two-factor).

You also need to make sure all the devices are signed onto the same iCloud account using the same Apple ID.

Once you select Allow your Apple Watch to unlock your Mac you will see a Turning On message. You may need to enter your password.

From now on if you wake up your Mac while wearing your Apple Watch it will automatically unlock.