Evans (22-1-1) handed a Davis (9-1) his first loss of his young career in a fight that was scored 50-45.
Evans moved into position to regain the light heavyweight title from Jon Jones, who was in attendance. Evans, 4-0 since losing the belt to Lyoto Machida in May 2009, will face Jones on April 21 in UFC 145.
"I will be ready to fight in April. There are a couple of things I need to work on," Evans said. "I am excited to finally fight Jon and give the people the fight they want so see."
Evans, a former Michigan State wrestler, controlled the first round by catching a kick from Davis and taking him down and keeping him there to end of the round. Evans finished the second round just as he did the first, catching another kick from Davis and keeping him on the ground to the end.
Davis, the 2008 NCAA wrestling champion for Penn State, did get a takedown in the third round, but it was after Evans landed an uppercut and a combination. Evans got in a right hand on Davis as the fourth round ended and used his superior striking game to control the fifth round.
Evans knows Jones quite well — and there's no love lost between them. He was friends and training partners with Jones before a falling out led to some bitter feelings.
"I definitely want to put it to bed, but more importantly, I want to get a chance to get my belt back. I feel like I can beat Jon Jones. I see some things in his game that I can capitalize on," Evans said. "Jon Jones has one thing that he has over other opponents that he doesn't have over me — we faced each other many times so I'm not really worried about the mystique of Jon Jones."
The Saturday night card was broadcast on FOX. UFC and the network announced a landmark seven-year deal last August, which will put four UFC shows on FOX each year. The FOX broadcast was the first official card under the new contract.
"I wanted to do better. I wanted to put on a more spectacular win for the Chicago fans and the FOX fans," Evans said. "I didn't do it like I wanted to or how I envisioned it, but at the same time I got the job done."
The capacity crowd at the United Center waited over three years for the return of the UFC to Chicago.
In the first fight on the main card, Chris Weidman (8-0) beat Demian Maia (15-4) in a lacklustre split decision.
In the second fight, Chael Sonnen (28-11-1) got his chance at title rematch against Anderson Silva for the middleweight title, unanimously outpointing Michael Bisping. Sonnen tapped out against Silva in the fifth round on Aug. 27, 2010. He initially lost his chance at a rematch with Silva after he tested with an elevated testosterone/epitestosterone ratio. After an appeal process, Sonnen was suspended for a year.
Sonnen says Silva has been reluctant to fight him.
"I can tell you this, I have never backed down and I never will, if he wants to fight of if he is willing to I will do my part," Sonnen said. "I'd rather fight real men like Mr. Bisping, who steps out on 10 days' notice and fights me. Those are the kind of guys I would like to give attention to, not some bum hiding in Brazil."