[12] Masvidal won his mixed martial arts debut by knockout on May 24, 2003, at HOOKnSHOOT: Absolute Fighting Championships 3.
[14] Masvidal garnered a 3–0 record in the now-defunct BodogFIGHT promotion, including decision victories over Keith Wisniewski, Steve Berger, and a head-kick knockout of PRIDE Fighting Championships and UFC veteran Yves Edwards.
[16] However, he was defeated in the semifinals by Toby Imada at Bellator 5, who won via inverted triangle choke submission in the third round.
[31] Following the championship bout, Masvidal fought Justin Wilcox at Strikeforce: Rockhold vs. Kennedy on July 14, 2012.
[33][34] Masvidal was expected to face Bobby Green on November 3, 2012, at Strikeforce: Cormier vs. Mir, but the bout was canceled along with the event itself.
[35][36] Replacing injured Gilbert Melendez, Masvidal was expected to face Pat Healy at Strikeforce: Marquardt vs.
[40] For his second bout with the promotion, Masvidal made a quick return to the Octagon as he replaced Reza Madadi in a fight against Michael Chiesa on July 27, 2013, at UFC on Fox 8.
[48] A bout with Bobby Green, first scheduled under the Strikeforce banner in 2012 before being scrapped, was expected to take place on September 27, 2014, at UFC 178.
[54] However, shortly after the fight was announced by the UFC, Green pulled out of the bout citing an injury and was replaced by Benson Henderson.
[59] Masvidal faced Cezar Ferreira in a welterweight bout on July 12, 2015, at The Ultimate Fighter 21 Finale.
[63] However, on November 14, it was announced that Masvidal would instead face Benson Henderson at the event after his scheduled opponent Thiago Alves pulled out of their fight.
[71] Masvidal was briefly linked to a bout with Kelvin Gastelum on November 5, 2016, at The Ultimate Fighter Latin America 3 Finale.
[72] However, on September 14, Gastelum was removed in favor of a fight against former lightweight title challenger Donald Cerrone at UFC 205, one week later.
[73] Subsequently, Masvidal was removed from the card entirely and instead faced Jake Ellenberger the following month at The Ultimate Fighter 24 Finale.
It was ruled a TKO after Ellenberger's toe was caught in the fence and the referee called a stop to the action resulting in the end of the fight.
[82] After a 16–month layoff, Masvidal faced Darren Till on March 16, 2019, in the main event at UFC Fight Night 147.
[86] Both fighters rushed in immediately with Masvidal catching Askren with a flying knee as he attempted a takedown, winning the fight via knockout 5 seconds into round one.
[93] In a unique situation, UFC President Dana White confirmed that the headlining bout was for a celebratory "Baddest Motherfucker" (‘BMF’) belt.
[109] On March 13, 2024, it was announced that Masvidal would face Nate Diaz on June 1, 2024 at the Kia Forum in Los Angeles, California[110] in a 10-round boxing bout at light heavyweight.
[117] Masvidal made his debut for All Elite Wrestling at AEW Grand Slam on September 24, 2021, alongside American Top Team, and attacked Chris Jericho and Jake Hager.
[121] In January 2022, Masvidal launched another MMA promotion, iKON FC, which would feature both UFC veterans and up-and-coming fighters.
Masvidal was arrested two days after the incident and charged with aggravated battery resulting in great bodily harm and one count of criminal mischief.
Masvidal surrendered to Miami Beach police and was detained at Turner Guilford Knight Correctional Center on a $15,000 bond; he was later conditionally released.
[126] At his arraignment on April 28, Masvidal was issued a stay away order and the aggravated battery charges were updated after Covington said he suffered a brain injury from the attack.
The resolution of this case concluded a legal chapter for Masvidal, who could have faced significant prison time and fines if convicted of the original felony charges.