Often, people would download third-party apps from Google Play store if they need to lock certain apps on their phone. There are many app lockers on the Play store, such as Vault, LOCKit, Folder Locker, Norton App Lock, Bitdefender Mobile Security, just to name a few.
Some smartphones, like Huawei, Mi phones, have the built-in feature to help users lock down any selected apps, like the Gallery, Phone, Messages, Contacts, on their phone without installing a separate app. We can just lock apps from the Settings. See how to lock apps on Huawei phone without using third-party apps. You can easily lock an application with one simple touch on your mobile.
Today, we will use a Redmi phone which is running on MIUI 9 in the demo to show you how to password protect an app on Xiaomi and Redmi devices. Once an app is locked, no one can open or access it without unlocking it using the correct PIN, Password, pattern or fingerprint.
Lock apps on Xiaomi & Redmi phones
Open Settings on your Mi phone. Find and tap on to open App Lock. If you can’t find this option, you might be using an old MIUI version.

If you run App Lock for the first time, you will be prompted to set pattern to lock apps. You can change the pattern or use PIN, password or fingerprint to lock apps later from its settings later.

Connect at least 4 dots to create a pattern. Draw the same pattern again. Then add your Mi Account to be able to reset your password or pattern in case you forget it.
Now you should see a list of all apps installed on your phone. Simply touch the ON/OFF toggle to lock or unlock an app on your Xiaomi or Redmi phone.

After that, when anyone tries to open a locked application, he or she will see the lock screen first. Without unlocking using the correct pattern, PIN, password or fingerprint, no one can access a locked app on your MI phone. A very handy way to prevent unwanted access to any app you deem private.