Ubuntu → Add MATE Desktop (24.04 / 24.10 / 25.04)

sudo apt update
sudo apt install ubuntu-mate-desktop

≈ 800–1400 MB depending on your current packages
Chooses lightdm or gdm3 (pick gdm3 if you want easy GNOME ↔ MATE switching)
After install → Log out → gear icon → select MATE

sudo apt update && sudo apt install ubuntu-mate-desktop lightdm

Reboot or log out → choose MATE at login screen.

sudo apt update
sudo apt install mate-desktop-environment

No Pluma, Atril, mate-tweak, system monitor, etc.

sudo apt install ubuntu-mate-desktop^

or

sudo apt install mate-desktop-environment-extras

# Classic look tools
sudo apt install mate-tweak

# (ONLY after MATE works well!)
sudo apt remove --purge gnome-shell ubuntu-gnome-desktop gnome-session

Warning: Do not remove GNOME packages until you’ve confirmed MATE works perfectly.

Works on Ubuntu 24.04 LTS, 24.10, 25.04 (and most derivatives)
MATE 1.26+ is very well maintained in Ubuntu repositories
Ubuntu MATE is also available as a full official flavor (separate ISO)
If you're on Debian / Linux Mint / Pop!_OS / Fedora → ask for different instructions