The gameplay of UFC 2009 Undisputed features three striking styles (Boxing, Kickboxing, Muay Thai) and three grappling styles (Wrestling, Judo, Brazilian Jiu-Jitsu), with each fighter carrying one style of each category. Simulating the likeness of UFC, two fighters go head-to-head in the Octagon using their suggested striking and grappling styles as well as signature moves commonly seen respective to each fighter.
The game offers several modes, including Exhibition for players to jump straight into gameplay with their favorite fighter, Classic Fights where fans can replicate memorable fights, and Create-A-Fighter to build a custom fighter. Players also have the freedom to create their own career with the ability to upload their created fighter into Career mode.