The Birmingham expo will be the first place in the country where fans can get their hands on the Rocksteady Studios title.
Warner Bros. Interactive Entertainment is showcasing three other titles at the event. Lord of the Rings: War in the North, Lego: Harry Potter years 5-7 and Happy Feet 2 will also be playable.
Modern Warfare 3 will be publicly shown for the first time in the UK, Activision confirmed last week. Other attendees include Sega, THQ, Sony Computer Entertainment, Electronic Arts and Microsoft.
Capcom, Codemasters, Konami and Namco Bandai were added to the roster this week.
GAMEfest will run from September 16 to 18 at Birmingham's NEC arena. Tickets are exclusive to GAME reward card holders.
> UK Gaming Expo Guide: Feature
Watch the Batman: Arkham City gameplay trailer below: