Can a Muslim make a will in the UAE, and how much can they leave freely?

Yes, but with limits. Under Sharia a Muslim can freely bequeath only up to one-third of their estate through a will (wasiyya), and generally not to someone who is already a fixed heir. The remaining two-thirds must pass by mandatory Sharia shares. Muslim residents can now also register wills through the ADJD. Seek qualified legal advice.