Changing lock screen wallpaper in Windows 11 is done on the lock screen page of Settings. It controls what you see when your PC starts or wakes from sleep. You can show rotating images from Microsoft, a single picture of your own, or a slideshow made from folders on your device.
- Open Settings → Personalization → Lock screen, then use Change your lock screen background to pick the background type.
- To use your own image, choose the picture type and select Browse for a lock screen picture.
- Press Windows + L to lock your PC and check the new background.