UFC president Dana White confirmed the event, UFC 138, to ESPN.com on Tuesday.
The event will air in the U.S. on Spike TV via same-day delay, White confirmed in a tweet Tuesday. The middleweight fight is also expected to be the first five-round non-title fight, a new policy White announced last month.
UFC 138 will be the organization's first visit to the U.K. since London hosted an event in October 2010.
Leben (26-7) is coming off a dominant performance over Wanderlei Silva at UFC 132 earlier this month. He recorded the fastest knockout of his career in that fight, at 27 seconds, and is 4-1 in his past five fights.
Munoz (11-2) has been on a similar run since joining the UFC in 2009. The California-based fighter is 6-2 with the promotion and will be seeking his third victory this year.
In his previous fight at UFC 131 in June, Munoz earned a hard-fought decision over Demian Maia.
Brett Okamoto covers mixed martial arts for ESPN.com.