Mixed martial arts (MMA) combines boxing, Muay Thai, and kickboxing into a competitive combat sport. Championship belts are awarded to top fighters in each weight class within a promotion. If a title is vacated, an interim champion may be named or a new champion crowned through a contender bout.

This list features titleholders from major MMA promotions, including the UFC, Strikeforce, KOTC, Pancrase, and regional leaders like UCMMA and MFC. While MMA lacks a unified weight class system, the Nevada State Athletic Commission’s (NSAC) classifications serve as the standard.