Fix Can’t Unlock iPhone with Apple Watch

If your iPhone stops unlocking with your Apple Watch, the fix is usually a quick settings toggle or a restart of both devices. Start by checking that Unlock with Apple Watch is enabled on your iPhone and that both devices have Bluetooth and Wi-Fi turned on, then restart both if needed.

Why This Feature Exists

Apple introduced Unlock with Apple Watch in iOS 14.5 as a convenience feature, especially useful during the COVID-19 pandemic when Face ID struggled with masks. The idea is simple: when your iPhone detects a paired, unlocked, and nearby Apple Watch, it bypasses Face ID and unlocks automatically. It was never meant to replace Face ID entirely—it’s a fallback for situations where Face ID can’t see your face clearly, like when wearing a mask or sunglasses.

The feature relies on a secure handshake between the two devices. Your Apple Watch must be on your wrist, unlocked, and within a few feet of the iPhone. The iPhone uses Bluetooth to detect the watch and Wi-Fi to confirm the connection, so both radios need to be active. If any of these conditions fail, the unlock won’t work.

How Unlock with Apple Watch Actually Works

When you try to unlock your iPhone with Face ID and it fails (or you’re wearing a mask), the iPhone sends a request to your Apple Watch. The watch vibrates and displays a notification asking you to double-click the side button to confirm. Once you confirm, the watch sends a cryptographic token back to the iPhone, and the phone unlocks.

This two-step process—detection plus confirmation—is what keeps the feature secure. The watch must be unlocked with its passcode, on your wrist, and you must actively approve the unlock. If the watch is off your wrist or locked, it won’t respond. If you don’t double-click, the iPhone stays locked.

Both devices need to be signed into the same Apple ID with two-factor authentication enabled. They also need to have Bluetooth and Wi-Fi on, and the iPhone must not be in Low Power Mode (which disables the feature). The watch should have a passcode set, and wrist detection must be enabled in the Watch app.

Step-by-Step Fixes to Try

Check the toggle: On your iPhone, go to Settings > Face ID & Passcode, enter your passcode, and scroll down to make sure “Apple Watch” is toggled on under “Unlock with Apple Watch.” If it’s off, turn it on.
Restart both devices: Restart your iPhone (press and hold the side button and volume button, then slide to power off) and your Apple Watch (press and hold the side button, then slide to power off). Turn them back on and try again.
Check Bluetooth and Wi-Fi: On the iPhone, open Control Center and confirm both Bluetooth and Wi-Fi are on. On the watch, swipe up to Control Center and check the same. Toggle them off and on if needed.
Ensure the watch is unlocked and on your wrist: The watch must be unlocked with its passcode and worn snugly on your wrist. If wrist detection is off, the feature won’t work.
Disable Low Power Mode: On the iPhone, go to Settings > Battery and turn off Low Power Mode if it’s on. This mode disables the unlock feature.
Reset the connection: In the Watch app on your iPhone, go to General > Reset and tap “Reset Sync Data.” This doesn’t erase your watch, just re-syncs the connection.
Unpair and re-pair: As a last resort, unpair the watch (Watch app > All Watches > tap the info icon > Unpair Apple Watch) and then pair it again. This will back up your watch data first, but it can fix deeper sync issues.

Common Problems and Misconceptions

One common misconception is that the feature works every time you pick up your iPhone. In reality, it only triggers after Face ID fails. If you have a mask on, Face ID will fail, and then the watch prompt appears. If you’re not wearing a mask, Face ID works normally and the watch isn’t involved.

Another issue is that the feature doesn’t work if your iPhone has just been restarted. After a reboot, you must enter your passcode once before the watch unlock will work again. This is a security measure to prevent someone from using your watch to unlock a phone that was turned off and stolen.

Some users report that the watch vibrates but the phone doesn’t unlock. This usually happens when the watch’s passcode is required (because it was taken off and put back on), or when the Bluetooth connection is weak. Move the phone closer to the watch, or check that the watch is actually on your wrist.

If you see a message on the iPhone saying “Unlock with Apple Watch is unavailable,” it often means the watch is locked or off your wrist. Unlock the watch with its passcode and try again.

When the Feature Won’t Work at All

There are a few situations where the feature is intentionally disabled. If you have a cellular Apple Watch and it’s in a different network state, or if your iPhone is in a different country with roaming, the feature may not work. Also, if you’ve recently changed your Apple ID password, you may need to re-enter it on both devices.

If you have an older Apple Watch (Series 3 or earlier) and a newer iPhone, compatibility isn’t an issue—Apple supports the feature on all watches that can run watchOS 7 or later. However, if your watch is running an older version of watchOS, update it via the Watch app on your iPhone.

Another rare case: if your iPhone has a repair with a non-genuine Face ID or battery, the feature might not work because the phone can’t verify the hardware. This is a security measure, and you’d need to contact Apple support for that.

Alternatives to Unlock with Apple Watch

If you can’t get the watch unlock to work, there are other ways to unlock your iPhone without using Face ID directly:

Passcode: Always the fallback. Type your six-digit code (or alphanumeric passcode) to unlock.
Face ID with a mask: On iPhone 12 and later, you can enable “Face ID with a Mask” in Settings > Face ID & Passcode. This uses a different facial recognition method that works with most masks, but it doesn’t work with sunglasses.
Apple Watch as a mask workaround: That’s exactly what the feature is for—when the mask option isn’t available on older iPhones.
Touch ID: If you have an iPhone SE (2nd or 3rd generation), you have Touch ID, which works with masks.

For most people, the watch unlock is a convenience, not a necessity. If it stops working, the fixes above usually resolve it within a few minutes.

Frequently Asked Questions

Why doesn’t my Apple Watch unlock my iPhone when I’m wearing a mask?

The feature should work with a mask, but it only triggers after Face ID fails. If Face ID succeeds (e.g., you’re wearing a mask that doesn’t cover your eyes, and you have “Face ID with a Mask” enabled), the watch won’t be used. Also, make sure the watch is unlocked and on your wrist, and that “Unlock with Apple Watch” is toggled on in Settings > Face ID & Passcode.

Do I need to double-click the side button every time?

Yes, every time the watch receives the unlock request, you must double-click the side button to confirm. This is a security step to prevent unauthorized unlocks. If you don’t confirm, the iPhone stays locked.

Will the feature work if my Apple Watch is in Airplane Mode?

No. Airplane mode disables Bluetooth and Wi-Fi on the watch, so it can’t communicate with the iPhone. Turn off Airplane mode on the watch (or on the iPhone, if it’s on) and try again.

Does the watch need to be charged?

Yes, the watch needs to have enough battery to operate. If it’s in Power Reserve mode (a low-battery state that only shows time), it won’t respond to unlock requests. Charge the watch and try again.

Can I use this feature with an Apple Watch that doesn’t have a passcode?

No. The watch must have a passcode set and wrist detection enabled. Without a passcode, the watch can’t securely confirm the unlock. You can set a passcode in the Watch app on your iPhone under Passcode.

What if I see “Cannot Unlock with Apple Watch” on my iPhone?

This message usually appears when the watch is locked, off your wrist, or out of range. Unlock the watch with its passcode, put it on your wrist, and bring it close to the iPhone. If it persists, restart both devices and check the toggle in Settings.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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