"It has become clear to me that I am no longer able to compete at the highest level of mixed martial arts," Stout stated. "Competing as a UFC fighter for the last 10 years has been something I will always look back on with great pride.
"I think my best days as a fighter are behind me and it would be a risk to my legacy and my health to continue competing. Therefore, I would like to announce my retirement from the sport of mixed martial arts."
Stout is probably best known for the back-and-forth nature of his bouts. The UFC awarded Stout a fight of the night bonus six times, as well as one knockout of the night bonus for a memorable shot against Yves Edwards at UFC 131 in 2011.
Fighting out of Ontario, Stout alternated wins and losses between 2011 and 2013, before hitting a three-fight skid. In his most recent appearance on Aug. 23, he suffered a knockout against 26-year-old Frankie Perez less than one minute in.