watchOS 2 offers an Activation Lock for your Apple Watch. It turns on automatically when you set up Find My iPhone on your paired iPhone. With Activation Lock, your Apple ID and password will be required before anyone can unpair your Apple Watch from your iPhone or pair and use your Apple smartwatch with a new iPhone.
To see if Activation Lock is on, open the Watch app on your iPhone, tap the My Watch tab, then tap My Watch. If you see Mark as Missing, then Activation Lock is on. You can also go to iCloud.com/activationlock and enter your device's serial number.
If your smartwatch is lost or stolen and Activation Lock is on, you can mark your Apple Watch as missing to stop anyone from reactivating your device without your permission. Alas, while you can use Find My iPhone Activation Lock with your Apple Watch, Find My iPhone can't be used to locate a lost Apple Watch or place one in Lost Mode. However, Mark as Missing will disable Apple Pay cards on your Apple Watch.
To turn on Mark as Missing from your Mac:
- Go to iCloud.com.
- Sign in with your Apple ID, and open Settings.
- Under "My Devices," click your Apple Watch.
- Click "Is this Device Missing," then click "Mark as Missing" to confirm.
If you find your Apple Watch, you can sign in to iCloud.com, open Settings, click your Apple Watch, and click Found this device.
To turn on Mark as Missing from your paired iPhone:
- Open the Watch app on your iPhone and tap the My Watch tab.
- Tap Apple Watch, then turn on Mark as Missing.
- Confirm that you want to unpair and that you need to enter your Apple ID to pair your Apple Watch again.
If you turn on Mark as Missing from your paired iPhone, you can't mark your Apple Watch as found later. If you find your Apple Watch, you need to pair it again.
To obtain watchOS 2, open the Apple Watch app on your iPhone (which must be running iOS 9) and tap through My Watch > General > Software Update. Make sure your watch is in Bluetooth range of your iPhone and connected to its charger.