Early career After the conclusion of his collegiate career, Mendes began to train in
mixed martial arts with
Team Alpha Male. He won the fight via unanimous decision, despite a cut over his right eye that was examined during the fight to see if he could continue. Mendes faced
Anthony Morrison, replacing an injured
Mackens Semerzier, on April 24, 2010 at
WEC 48. He won the bout via first round submission. Mendes faced
Cub Swanson on August 18, 2010 at
WEC 50. He won the fight via unanimous decision (30–27, 29–28, and 29–28). Mendes was able to utilize his improved striking to complement his superior wrestling to dictate where he wanted to take the action. During the fight, Mendes used an unorthodox move when he front flipped on Vazquez who was on the ground, to land on him.
Ultimate Fighting Championship On October 28, 2010,
World Extreme Cagefighting merged with the
Ultimate Fighting Championship. As part of the merger, all WEC fighters were transferred to the UFC. Mendes made his UFC debut against returning veteran and judo black belt
Michihiro Omigawa on February 5, 2011 at
UFC 126. He won the fight via unanimous decision. Following
UFC 129,
Dana White mentioned in the post-fight press conference that Mendes may have a shot at the title against UFC featherweight champion
José Aldo. Although the two were expected to fight on August 6, 2011 at
UFC 133, Aldo would be sidelined until October recovering from various injuries sustained during his fight with
Mark Hominick. Mendes instead faced
Rani Yahya at the event. He won the fight via unanimous decision. Mendes fought
UFC Featherweight Champion José Aldo on January 14, 2012 at
UFC 142, losing at 4:59 of the first round via KO, giving Mendes his first professional loss. Mendes next faced
Cody McKenzie on July 7, 2012 at
UFC 148. He won the fight via first-round TKO due to a body punch. Mendes was expected to face
Hacran Dias on December 15, 2012 at
UFC on FX 6. However, in just days before the event, Dias pulled out of the bout, citing a shoulder injury, and he was replaced by promotional newcomer
Yaotzin Meza. Mendes defeated Meza via KO at 3:38 in the first round. Mendes was expected to face
Manvel Gamburyan on February 23, 2013 at
UFC 157. However, Gamburyan pulled out of the bout, citing a thumb injury. Subsequently, Mendes was pulled from the card as a suitable replacement could not be found on short notice. Mendes was expected to face
Clay Guida on April 20, 2013 at
UFC on Fox 7. However, it was revealed on March 15 that Guida had pulled out of the bout, citing an injury, and he was replaced by
Darren Elkins. Mendes won the fight by TKO at 1:08 in the first round. A rescheduled bout with Guida took place on August 31, 2013 at
UFC 164. After a close first and second round, Mendes finished Guida via TKO by punches in the third round and became the first man to ever finish Guida by strikes. The win also earned Mendes his first
Knockout of the Night bonus award. Mendes faced
Nik Lentz on December 14, 2013 at
UFC on Fox 9. He won the fight via unanimous decision. A rematch with
José Aldo was expected to take place on August 2, 2014, as the event headliner at
UFC 176 for the UFC Featherweight Championship. However, in early July, Aldo pulled out of the bout with an injury. The rematch with Aldo was subsequently rescheduled and took place on October 25, 2014, at
UFC 179. He became the first man to knock down Aldo dropping him with a left hand in the first round. Mendes and Aldo both rocked each other with clean punches, Mendes would go on to lose the fight via unanimous decision. Despite the loss on the scorecards, Mendes was awarded his first
Fight of the Night bonus award for the bout. The fight won
World MMA Awards 2015
fight of the year award. Mendes faced
Ricardo Lamas on April 4, 2015 in the main event at
UFC Fight Night 63. Mendes won the fight via TKO in the first round. The win also earned Mendes his first
Performance of the Night bonus award. On May 18, 2015,
Dana White tweeted that Chad Mendes had agreed to an eight-fight contract with UFC.
José Aldo was expected to face
Conor McGregor on July 11, 2015 at
UFC 189 for the undisputed
UFC Featherweight Championship. However, in the days leading up to the fight, Aldo pulled out of the bout because of a rib injury he sustained in training. Mendes stepped in as a short notice replacement to face McGregor for the interim championship. Mendes lost the fight via TKO in the second round. Mendes faced
Frankie Edgar on December 11, 2015 at
The Ultimate Fighter 22 Finale. He lost the fight via knockout in the first round. After returning from his suspension and two-and-a-half years away from the sport, Mendes faced
Myles Jury on July 14, 2018 at
UFC Fight Night 133. He won the fight via TKO in the first round. This win earned him the
Performance of the Night award. Mendes faced
Alexander Volkanovski on December 29, 2018 at
UFC 232. He lost the fight via TKO in the second round. This fight earned both participants
Fight of the Night honors. Following the loss, Mendes announced his retirement from the sport.
Global Fight League Mendes was scheduled to come out of retirement to face Maike Linhares in the inaugural Global Fight League event on May 24, 2025 at GFL 1. However, all GFL events were cancelled indefinitely. ==Bare-knuckle boxing career==