CM Punk is joining UFC. (Getty Images)

Former pro wrestler CM Punk is transitioning into the Octagon after he signed a multifight deal with UFC. 

Punk plans to debut in mixed martial arts in 2015 and could be ready to fight within six months. Punk, whose birth name is Phil Brooks, has never fought an MMA bout before, but he said the decision was about meeting a new challenge. 

"It was actually a really easy decision to make, and time will tell how wise a decision it was," Brooks told Associated Press. "I finally found something I can put 100 percent of myself into. ... I'm a guy who likes goals and challenges, and this is the biggest challenge I've ever put in front of myself." 

UFC president Dana White announced Punk's inclusion on Saturday night during UFC 181, a significant announcement in front of many of UFC's sponsors. 

"We're going to give him an opportunity," White said. "He's been training a lot in mixed martial arts, and we're going to give him a shot. This guy can definitely sell some units." 

Punk, 36 and a former WWE wrestler, plans to start as a 185-pound middleweight. 

"The big business is your first fight," Brooks said, of why he chose to join UFC instead of a smaller MMA outfit. "Win, lose, or draw, if I fought somewhere else, maybe a little bit of the luster would've gotten knocked off. This is very much a business as well as fighting. There's both sides of it and I think it merged perfectly."