How to Change the Mac Login Screen Background

Customising Your Mac’s First Impression

When you wake your Mac from sleep or turn it on in the morning, the first thing you see is the login screen. By default, Apple ties the background image of this login screen directly to your desktop wallpaper. If you have a picture of a mountain range set as your desktop wallpaper, that same mountain range will appear blurred out behind your profile picture on the login screen.

For many users, this default behaviour is perfectly fine. However, if you share a Mac with multiple family members, or if you use your Mac in a corporate environment where the login screen needs to display a company logo while allowing employees to keep their own personal desktop wallpapers, you will need to decouple the two images.

Changing the login screen background independently of the desktop wallpaper is surprisingly difficult in modern versions of macOS (Ventura and Sonoma). Apple removed the simple graphical menu option to do this several years ago. To change it today, you must replace a specific system file hidden deep within the macOS folder structure.

Warning: This process involves modifying internal system files. While the steps below are safe if followed exactly, you should ensure your Mac is backed up using Time Machine before proceeding.

Step 1: Prepare Your New Image

macOS requires the login screen background image to be a very specific file type and have a very specific name. You cannot simply use a standard JPEG.

1. Find the high-resolution image you want to use for your login screen.
2. Double-click the image so it opens in the default Preview application.
3. In the menu bar at the top of the screen, click File and select Export.
4. Change the Format drop-down menu to HEIC (High-Efficiency Image Container).
5. Change the Save As file name exactly to: lockscreen.heic (ensure it is all lowercase).
6. Save this file to your Desktop so it is easy to find.

Step 2: Locate the Hidden System Folder

You must now find the folder where macOS stores its default login screen image.

1. Open a new Finder window.
2. Click on Go in the top menu bar.
3. Select Go to Folder… from the drop-down menu (or press Command + Shift + G).
4. A search bar will appear. Carefully copy and paste this exact file path into the box:
   /Library/Caches/Desktop Pictures/
5. Press the Return key.

You should now see a folder containing a string of numbers and letters (this string is your user profile’s unique UUID). Double-click to open this folder. Inside, you will see a file called lockscreen.png or lockscreen.heic. This is the image currently being displayed on your login screen.

Step 3: Replace the File and Set Permissions

You must replace the existing file with the new one you created, but because this is a system folder, macOS will ask for your administrator password to confirm the change.

1. Drag the lockscreen.heic file you saved on your Desktop into this folder.
2. macOS will ask if you want to replace the existing file. Click Replace.
3. You will be prompted to enter your Mac’s administrator password (or use Touch ID) to authorise the replacement.

The image is now replaced, but there is one final, crucial step. You must lock the file so macOS does not automatically overwrite it the next time you change your regular desktop wallpaper.

4. Click once on the new lockscreen.heic file inside the folder to select it.
5. Press Command + I (or right-click and select Get Info).
6. In the Get Info window that appears, look for the checkbox labelled Locked and tick it.
7. Close the Get Info window.

Step 4: Restart Your Mac

The changes will not take effect immediately while you are logged in. To see your new custom login screen, you must restart your computer.

1. Click the Apple Logo in the top left corner.
2. Select Restart…

When the Mac boots back up, you will be greeted by your custom image on the login screen, completely independent of whatever desktop wallpaper you choose to use once logged in.