Stann most recently dropped from light-heavyweight to middleweight after a dominant and punishing decision loss to undefeated UFC newcomer Phil Davis.
He made his middleweight debut against Mike Massenzio. After being thoroughly dominated on the ground by Massenzio for the first two rounds, Stann locked up a tight triangle in the third round to earn a victory, an impressive divisional debut and his first victory by submission.
Stann next faced fellow heavy hitter in veteran Chris Leben in what was anticipated to be a hell of a war. Stann defeated Leben via a very shocking first-round technical knockout to break into the top echelon of the middleweight division. He was next set to fight the legend Wanderlei Silva but instead the opponent was changed to the returning former Sengoku middleweight champion Jorge Santiago. Stann defeated Santiago via second-round knockout.
He was next heavily rumored to be set to fight against Mark Munoz in a number-one contender match.
Instead, Stann was next set to face fellow contender Chael Sonnen. The fight was likely to decide another contender for Anderson Silva's middleweight title. Sonnen defeated Stann via second round arm triangle choke submission. It was his first loss as a middleweight.
Stann next signed to face fellow striker, the Italian Alessio Sakara. He defeated Sakara via first-round knockout and gained widespread attention for stopping the fight without the referee's help after he saw that Sakara was unable to continue.
Stann next signed to face former Bellator middleweight champion and Pride veteran and UFC newcomer Hector Lombard. He was unfortunately injured and replaced by Tim Boetsch. After recovering, Stann faced Michael Bisping losing a unanimous decision.
Stann then signed in December 2012 to face legend Wanderlei Silva in Japan at light-heavyweight. The fight took place at the start of March 2013. Stann and Silva brawled it out for nearly ten minutes in an early candidate for 2013's Fight of the Year before Silva knocked Stann unconscious. Stann was heartbroken after the loss but there could be no doubt that he earned thousands of new fans.
Months after the loss Stann retired from mixed martial arts in July 2013.
- Brian Stann vs. Steve Cantwell 1 - The fight was the WEC debut of both undefeated men and the first loss of Steve Cantwell. First Lieutenant Brian Stann dedicated the victory to his four fallen comrades.
- Brian Stann vs. Jeremiah Billington - The fight was the WEC debut of Jeremiah Billington.
- Brian Stann vs. Steve Cantwell 3 - The fight was the rubber match between the two men.
- Phil Davis vs. Brian Stann - The fight was the UFC debut of undefeated Phil Davis and the last fight as a light-heavyweight for Stann.
- Brian Stann vs. Mike Massenzio - The fight was Stann's middleweight debut and his first submission victory. The fight was the first fight reffed by Big John McCarthy in the UFC since the fight between Clay Guida and Roger Huerta.
- Brian Stann vs. Chris Leben - The fight was only the second time that iron-chinned Chris Leben had been definitively finished by punches.
- Brian Stann vs. Jorge Santiago - The fight was Jorge Santiago's return to the UFC.
- Chael Sonnen vs. Brian Stann
- Brian Stann vs. Alessio Sakara
"People often talk to me about Brian and they say, ‘How are you going to get in brian’s head? What are you gonna do to get in Brian’s head?’ Do you not understand that this man went into enemy territory at 122-degree temperature, he put on 80 pounds of gear and literally fought a tank. What am I gonna do to get in his head? Nothing. Do you think he’s gonna be scared of me? He wouldn’t be scared of five of me."
- Chael Sonnen on Stann.