How to lock your Mac remotely

The short answer

You lock a missing Mac remotely with Apple's Find My. From another Apple device, or from a web browser at icloud.com/find, you sign in with your Apple Account, select the Mac, and choose Mark As Lost. That locks the Mac and can show a message and a contact number on its Lock Screen, so a finder can reach you without getting into your files. There is one hard requirement: Find My had to be turned on for that Mac beforehand. You cannot enable it after the Mac is already out of your hands.

What you need in place first

Remote lock is not something you switch on after the fact. It depends on Find My Mac having been active on the machine already, which is why the most useful step is the one you take while the Mac is still with you.

Lock the Mac from another device

Once the Mac is missing and Find My was already on, you can lock it from any browser or any other Apple device signed in to your account.

If the Mac is offline

A remote lock is not instantaneous when the Mac has no connection. If the Mac is online, it locks straight away. If it is offline, the lock is queued and applies the next time the Mac connects to the internet, and any message you set is not shown until then. This is the central limitation of every remote-lock tool: it can only reach a device that eventually comes back online, and it does nothing in the window before that happens.

Unlocking, and the difference between lock and erase

Recovering the Mac is deliberately one-sided. As Apple puts it, you cannot unlock a Mac online or on another device; you can only unlock it on the Mac you marked as lost, using the Apple Account password or the passcode you set. That is the point of the feature, but it means you should be sure of those credentials before you lock.

Find My also offers Erase as a separate, heavier option. Marking as lost keeps your data on the Mac behind the lock, though whether that lock actually protects the data from someone who powers the Mac down and works on the drive at leisure depends on whether FileVault disk encryption was switched on; erasing wipes the Mac's contents entirely. Erase is the last resort when you have given up on recovering the device, and even then Activation Lock keeps it tied to your Apple Account. For the everyday case of stepping away from a Mac you still have, neither of these is the right tool, which is the rest of this guide.

The gap a remote lock leaves open

Find My is reactive. It is built for the moment the Mac is already gone, and it works only if Find My was on beforehand and the Mac reaches the internet again. What it cannot help with is far more common than theft: the few minutes your unlocked Mac sits on your desk after you walk to the coffee machine, step into a meeting, or leave for the restroom. In that window a passer-by can read what is on the screen or copy a file, and you would never know to reach for Find My at all. The native screen lock is supposed to cover this, but it locks on a fixed inactivity timer rather than on whether you are actually there, which is why a Mac so often does not lock when you leave yet locks while you are still sitting and reading.

Closing the everyday gap with presence-based locking

Presence-based locking is the proactive counterpart to a remote lock. Instead of waiting for you to notice the Mac is gone and reach for another device, it locks the screen within seconds of you genuinely leaving the desk. This is the approach Peeku uses to auto-lock the moment you walk away, using three signals that all stay on your Mac:

• Face presence from the built-in camera, analysed locally with Apple's Vision framework. No image or video leaves the device, and it detects whether a face is present, not who it is.
• An optional Apple Watch proximity gate over Bluetooth, so the Mac only locks when both the camera and the Watch agree you have left.
• Keyboard and mouse idle time, used to avoid reacting to a brief pause at the keyboard.

The two tools answer different questions and sit well together. Keep Find My switched on for the rare day a Mac is lost or stolen, and let presence-based locking close the unattended-desk window that Find My was never meant to cover. Detection runs entirely on your Mac with no account and no cloud face data, as the guide on privacy-first, on-device auto-lock explains. Two honest caveats: any lock is only secure if you set "Require password after sleep or screen saver: immediately" in System Settings, so do that first either way, and the full locking app ships free outside the Mac App Store, on Gumroad and as a notarised DMG, because the App Store sandbox blocks the system screen-lock calls. The two-minute setup guide covers the rest.

Quick reference

• Lock a lost or stolen Mac: sign in at icloud.com/find or the Find My app, select the Mac, choose Mark As Lost. Requires Find My Mac to have been on beforehand.
• Apple silicon Mac: locked with your Apple Account password. Intel Mac: locked with a numerical passcode you create.
• Offline Mac: the lock applies the next time it connects to the internet; the message appears only then.
• Unlocking: only possible on the Mac itself, never remotely. Erase is a separate, last-resort wipe.
• The everyday unattended-desk window: remote lock does not help here. Presence-based locking does, by locking when you leave and not while you are present.