Early career Costa made his professional MMA debut in his native country of Brazil in February 2012. Eventually, his brother convinced their mother to support Paulo monetarily for a year in order to pursue his professional martial arts career.
The Ultimate Fighter: Brazil Costa was chosen to be a fighter on
The Ultimate Fighter: Brazil 3. In the opening elimination round, he defeated José Roberto via submission (
guillotine choke) in the second round. Costa was the second middleweight fighter chosen by coach
Wanderlei Silva. His next fight was against Márcio Alexandre Jr., and Costa lost via
split decision after three rounds.
Ultimate Fighting Championship Costa made his promotional debut on 11 March 2017, at
UFC Fight Night 106 against
Garreth McLellan. He won the fight via TKO in the first round, earning his first
Performance of the Night award. Costa faced
Oluwale Bamgbose on 3 June 2017, at
UFC 212. He won the fight via TKO in the second round. After the fight with Bamgbose, UFC offered a new contract, but the parties did not come to an agreement on the financial terms. The UFC then proposed a fight with former welterweight champion
Johny Hendricks, with a promise to renegotiate after the bout. Costa faced Hendricks on 4 November 2017, at
UFC 217. He won the fight via TKO in the second round. After the bout Costa signed a new, multi-fight contract. However, Costa pulled out of the fight in mid-March with an arm injury. In turn, promotion officials elected to pull Hall from that event entirely and reschedule the pairing for 7 July 2018, at
UFC 226. Costa won the fight via technical knockout in round two. The win earned him his second Performance of the Night award. Costa was scheduled to face
Yoel Romero on 3 November 2018, at
UFC 230. However, Romero indicated in mid-August that, while he had been cleared to fight, his medics had recommended that he wait another four to five months to allow facial injuries incurred during his most recent fight to fully heal. The bout was rescheduled again, and was expected to take place on 27 April 2019, at
UFC on ESPN+ 8. Costa was removed from the card for an undisclosed reason. He was replaced by
Ronaldo Souza. Romero then pulled out of the fight due to pneumonia, and Costa was scheduled to face Souza, but a
United States Anti-Doping Agency (USADA) investigation prevented Costa from participating, so neither Romero nor Costa competed in the event. It was revealed that Costa had been suspended for six months by USADA and Comissão Atlética Brasileira de MMA (CABMMA) for receiving prohibited
intravenous infusions (IV) more than 100 mL in 12 hours after the weigh-ins in June 2017 at UFC 212 against
Oluwale Bamgbose and November 2017 at UFC 217 against
Johny Hendricks. Costa was fined a third of his purse of the fights, which were reverted to his opponents. The suspension was retroactive to 10 August 2018, and Costa was eligible to fight again in February 2019. On 23 March 2020, Lucas Penchel
MSc, who provided the infusions in question, accepted a two-year ban from USADA, starting on 13 March 2020. Costa finally faced Romero on 17 August 2019, at
UFC 241. He won the fight via unanimous decision. This fight earned him the
Fight of the Night award. On the strength of his five-fight win streak in the UFC, Costa faced
Israel Adesanya for the
UFC Middleweight Championship on 27 September 2020 at
UFC 253. He lost the fight via technical knockout in the second round, making this his first professional loss. Costa was scheduled to face
Robert Whittaker on 17 April 2021 at
UFC on ESPN 22. However, on 16 March Costa withdrew from the fight due to illness, and was replaced by
Kelvin Gastelum. Costa was scheduled to face
Jared Cannonier on 21 August 2021 at
UFC on ESPN 29. However, on 4 June, Costa withdrew from the bout for unknown reasons. Costa later claimed he never signed the bout agreement and cited issues with his payment, while not confirming them as the reason for his withdrawal. Costa faced
Marvin Vettori in a light heavyweight bout on 23 October 2021 at
UFC Fight Night 196, which was originally scheduled as a middleweight contest and briefly changed to a catchweight bout. Costa received widespread criticism for showing up twenty-five pounds over the middleweight limit. Costa lost the fight via unanimous decision. Costa was scheduled to face former
UFC Middleweight champion
Luke Rockhold on 30 July 2022, at
UFC 277. However, the bout was postponed to
UFC 278 for unknown reasons. Costa won the fight via unanimous decision. The fight earned him the
Fight of the Night award. Costa was scheduled to face
Robert Whittaker on 12 February 2023, at
UFC 284. However, Costa disputed the official announcement by the promotion indicating he had never signed a contract and the fight would not take place. Costa was scheduled to face
Ikram Aliskerov on 29 July 2023, at
UFC 291. However, it was announced on 19 July that the promotion opted to scrap the pairing and instead move him to face
Khamzat Chimaev on 21 October 2023, at
UFC 294. In turn, Costa pulled out of the fight due to injury, and was replaced by
Kamaru Usman. Costa faced former
UFC Middleweight champion
Robert Whittaker on 17 February 2024, at
UFC 298. Despite almost finishing Whittaker at the end of the first round with a head kick, Costa ended up losing the bout by unanimous decision. Costa faced former
UFC Middleweight champion
Sean Strickland on 1 June 2024, at
UFC 302. He lost the fight by split decision. Costa was scheduled to face
Roman Kopylov on 28 June 2025, at
UFC 317. However, for unknown reasons, the bout was moved to
UFC 318, which took place on 19 July 2025. Costa won the fight by unanimous decision. Costa was scheduled to face
Sharabutdin Magomedov on 22 November 2025, at
UFC Fight Night 265. However, Magomedov withdrew due to undergoing nose surgery. Costa was scheduled to face Brunno Ferreira on 7 March 2026 at
UFC 326. However, Costa pulled out on December 26 due to undisclosed reasons and was eventually replaced by
Gregory Rodrigues.
Light Heavyweight Moving up to light heavyweight, Costa faced
Azamat Murzakanov on 11 April 2026, in the co-main event of
UFC 327. Costa won the bout by technical knockout via head kick in the third round, handing Murzakanov the first loss of his mixed martial arts career. ==Championships and accomplishments==