- How to lock Messenger chats with App lock
- What Messenger App lock does and doesn't do
- Can you lock a single chat on Messenger?
- Lock Messenger with your phone's own settings as well
- Lock your Messenger account as well as your chats
- Locking Messenger for a small-business phone
- If Messenger App lock isn't working
- Frequently asked questions
To lock Messenger chats, open Messenger, go to Settings, then Privacy and safety, then App lock, and turn it on. Messenger will ask for your face, fingerprint or device passcode each time it opens. It locks the whole app, not one chosen chat, and it doesn't apply to computers.
Plenty of people ask how to lock a Messenger chat, usually because a phone gets passed around: to the kids, to a partner, to a colleague at the till. I'll be straight about what Messenger's help centre offers, because it's not quite what the search phrase suggests. It offers a way to lock the whole Messenger app on your phone. It doesn't describe a feature for locking one chosen conversation behind its own passcode. Here's how the app lock works, what it protects, what it doesn't and the options that do cover individual chats. Menus vary by app version.
How to lock Messenger chats with App lock
The help article is called Lock your Messenger app on your device. It says that with app lock on, Messenger asks for your face or fingerprint (or your device passcode method) before it opens. The route to switch it on is:
- Open Messenger and tap your profile picture or Menu.
- Go to Settings, then Privacy and safety.
- Tap App lock and turn it on.
- Choose how soon Messenger should lock again after you leave it.
On iPhone you need Face ID or Touch ID and a device passcode set up first. On Android the help centre describes the same feature using your fingerprint or other device authentication. If you can't see the setting, update Messenger. My guide to updating Messenger takes you through that.
What Messenger App lock does and doesn't do
- It locks the app. Anyone opening Messenger on your phone has to authenticate first, so every chat inside is covered at once.
- Your face or fingerprint data stays on your device. The help centre says Facebook receives no information about your face or fingerprint.
- Notifications can still appear while the app is locked. Tapping one asks for your ID before you reply, but the help centre says you can also reply to locked notifications without authenticating.
- It doesn't apply to computers. It's a phone and tablet feature.
- If you delete and reinstall Messenger, you have to turn app lock on again.
That notification detail matters. If you're worried about someone glancing at your lock screen, change what your phone shows in notifications through your phone's own settings. App lock alone won't hide that preview.
Can you lock a single chat on Messenger?
This is the part many articles blur. From the help pages I've read, Messenger doesn't describe a feature where you pick one conversation and lock it behind a separate passcode. If a website or an app tells you it will, treat it with suspicion, because tools that ask for access to your account can put it at risk. Instead, these Messenger features do related jobs:
| Feature | What it does | What it doesn't do |
|---|---|---|
| App lock | Asks for face, fingerprint or device passcode before Messenger opens | Doesn't lock one chat only; doesn't work on a computer |
| Archive | Hides a chat from your inbox | Doesn't need a passcode to open the Archive folder |
| End-to-end encryption | Means only you and the other person can read an encrypted conversation | Doesn't stop someone using your left open phone |
| Mute | Silences alerts | Doesn't hide anything |
Archiving is the closest thing to hiding a chat, and I've covered it in my guide to archiving chats on Messenger. But anyone who can open your Messenger can open the Archive folder, so pair it with app lock.
Lock Messenger with your phone's own settings as well
Messenger's lock covers the app. Your phone has its own protection, and the two work best together. Use a strong screen lock, keep your operating system up to date and don't leave your phone left open on a table. On a shared family device, check whether your phone offers a separate profile or guest mode, as it may keep your apps apart.
Lock your Messenger account as well as your chats
A lock on the app does nothing about someone logging into your account from another device. The help centre's security pages recommend a strong, unique password and two-step login. If you've noticed anything odd, such as messages you didn't send, read my guide to the signs that a Facebook account was hacked and secure your account first.
For end-to-end encrypted chats, the help centre also explains that history doesn't appear automatically on a new device and needs restoring with a PIN, an Apple or Google account, a one-time code or a 40-character code. Keep that restore method somewhere safe. It's a different thing from a lock, but it matters if you change phones.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
Locking Messenger for a small-business phone
If customers message you on Messenger, your phone holds order details, addresses and names. App lock is a quick safeguard. Switch it on, keep the re-lock timing short, and don't pass the phone to anyone who doesn't need it. If more than one person handles your messages, using each person's own login is safer than sharing one account.
If Messenger App lock isn't working
Check these in order. Make sure Face ID, Touch ID or your fingerprint is set up on the phone itself, since app lock depends on it. Update Messenger. Turn the setting off and on again. If you've reinstalled the app, switch it on again, as the help centre says you must. And note the feature only exists on phones and tablets, so don't look for it on a computer.
Frequently asked questions
How do I lock Messenger chats?
Open Messenger, go to Settings, then Privacy and safety, then App lock, and turn it on. Messenger then asks for your face, fingerprint or device passcode before it opens. Menus vary by app version.
Can I lock just one conversation on Messenger?
The help pages I checked don't describe locking a single chat with its own passcode. App lock covers the whole app.
Does App lock work on a computer?
No. The help centre says it doesn't apply to computers.
Do I need to set it up again after reinstalling Messenger?
Yes. The help centre says that if you delete and reinstall Messenger, you have to turn app lock on again.
Does Facebook get my fingerprint or face data?
The help centre says the biometric data stays on your device and Facebook receives no information about your face or fingerprint.
Will notifications still show when Messenger is locked?
They can. Tapping a notification asks for your ID, but the help centre says you can also reply to locked notifications without authenticating.
