Mendes was a two-time All-American in wrestling for Cal Poly in San Luis Obispo, California, and finished his career with a record of 64-14.
After wrapping up college, Mendes joined Team Alpha Male to pursue MMA in 2008. His wins in Palace Fighting Championships earned him a spot in the WEC, which he fought and won four times in before the UFC picked him up.
In his third fight in the UFC, Mendes fought Jose Aldo for the featherweight title, which he lost by a vicious knockout courtesy of a knee from the champ. After picking up five more wins including victories over Clay Guida, Nik Lentz and Cody McKenzie, he earned another shot against Aldo at UFC 179.
This time, the bout went the distance but Aldo remained on top. After Aldo suffered an injury, Mendes had a third shot at the title, this time against Conor McGregor for the interim belt. After two rounds, McGregor overwhelmed him to earn a TKO win.
Attempting to bounce back, Mendes fought Frankie Edgar in December 2015, but was knocked out in the first round by the New Jersey native.