Early career Harris competed as an amateur from 2009 to 2010, compiling a record of 4–1. He made his professional debut on March 15, 2011, when he faced Justin Thornton at HEF: Hess Extreme Fighting. He won via first-round TKO, just sixteen seconds into the first round. Following this, Harris compiled a record of 6–1, with wins over Tony Melton and UFC veteran
Anthony Hamilton, before signing with UFC in the fall of 2013.
Ultimate Fighting Championship On September 19, 2013, it was announced that Harris had signed with the UFC, and he faced fellow newcomer
Jared Rosholt at
The Ultimate Fighter 18 Finale on November 30, 2013. Despite dropping Rosholt in the first round, Rosholt rallied back and Harris lost the fight via unanimous decision. In his second fight with the promotion, Harris faced
Nikita Krylov at
UFC on Fox 10 on January 25, 2014. Though he was the considerable favorite coming into the bout, Harris was staggered by a head kick from Krylov, and after follow-up strikes on the ground from Krylov, he lost the bout via TKO, just 25 seconds into the first round. After dropping to 0–2 in the UFC, Harris was subsequently released from the promotion.
Titan Fighting Championship Following his UFC release, Harris signed with
Florida based promotion Titan FC. He faced D.J. Linderman at Titan FC 28 on May 16, 2014. He won the fight via first-round knockout. He was expected to face
Dave Herman at
Titan FC 30 on September 26, 2014. However, Harris pulled out of the bout due to a back injury and the fight was postponed. The bout with Herman was rescheduled and was expected to take place on December 19, 2014. However, Harris resigned with the UFC, and he was replaced by
Jon Madsen.
Return to UFC After
Daniel Omielańczuk was forced to pull out of his bout with
Soa Palelei due to a thumb injury, Harris resigned with UFC and faced Palelei at
UFC Fight Night 55 on November 7, 2014. He lost the fight via second-round TKO. Harris faced promotional newcomer Cody East on April 23, 2016, at
UFC 197. He won the fight via TKO in the first round. Harris next faced
Shamil Abdurakhimov on October 1, 2016, at
UFC Fight Night 96. He lost the fight via split decision. Harris faced
Chase Sherman on January 15, 2017, at
UFC Fight Night 103. He won the fight by knockout in the second round. Harris made his next appearance against
Cyril Asker on June 17, 2017, at
UFC Fight Night 111. He won the fight early in the first round via TKO due to a combination of elbows and punches. Harris was expected to face
Mark Godbeer on October 7, 2017, at
UFC 216 before a fight-day injury to
Derrick Lewis took him out of his scheduled fight with
Fabrício Werdum. As a result, Harris moved on to face Werdum, and Godbeer was pulled from the event. Harris lost the fight via submission in the first round. The bout with Godbeer was quickly rescheduled and took place on November 4, 2017, at
UFC 217. Harris lost the bout by disqualification after Harris hit Godbeer with a head kick following the referee calling a time out due to a groin strike. Harris faced
Daniel Spitz on June 1, 2018, at
UFC Fight Night 131. He won the fight via knock out in the second round. Harris faced
Andrei Arlovski on December 29, 2018, at
UFC 232. He won the fight via split decision. It was reported on January 26, 2019, that Harris tested positive for LGD4033, and
selective androgen receptor modulators (SARMs) like ostarine, and he was temporarily suspended by
California State Athletic Commission (CSAC). In February, Harris was suspended for four months and fined $4,000. The fight result was overturned to a no contest. Per the CSAC, Harris was able to prove the positive test resulted from a tainted supplement and the commission does not believe he was an intentional doper, hence the shorter suspension. Harris was expected to face
Alexey Oleynik on May 4, 2019, at
UFC Fight Night 151. However, on April 3, 2019, it was announced that Oleinik would face
Alistair Overeem at
UFC Fight Night 149 after
Alexander Volkov withdrew from the event. He was replaced by
Serghei Spivac. Harris won the fight via TKO in the first round. This fight earned Harris his first
Performance of the Night bonus award. The bout between Harris and Oleynik was rescheduled and took place on July 20, 2019, at
UFC on ESPN 4. Harris won the fight via knockout just 12 seconds into the first round. This win earned Harris his second consecutive Performance of the Night bonus. Harris was expected to face
Alistair Overeem on December 7, 2019, at
UFC on ESPN 7. However, Harris pulled out on November 1, 2019, due to the ongoing search for his missing step-daughter. Harris was expected to face
Alistair Overeem on April 11, 2020, at
UFC Fight Night: Overeem vs. Harris. The pairing was previously scheduled to headline
UFC on ESPN 7 in December 2019. Due to the
COVID-19 pandemic, the event was eventually postponed. The match was rescheduled to May 16, 2020, at
UFC on ESPN: Overeem vs. Harris. Despite hurting, and almost finishing Overeem in the first round, Harris went on to lose via second-round TKO. Harris faced
Alexander Volkov on October 24, 2020 at
UFC 254. He lost the fight via technical knockout in round two. Harris faced
Marcin Tybura on June 5, 2021, at
UFC Fight Night: Rozenstruik vs. Sakai. He lost the fight via TKO in round one. Harris was scheduled to face
Tai Tuivasa on October 30, 2021, at
UFC 267. However, Harris pulled out of the bout for unknown reasons. After a 2-year layoff, Harris was scheduled to face
Josh Parisian on July 15, 2023, at
UFC on ESPN 49. However, the bout was scrapped by Combat Sports Anti-Doping (CSAD) due to a potential anti-doping policy violation by Harris. He was given a 4-year suspension and will be eligible to compete again on July 11, 2027. On March 27, 2025, it was reported that Harris was removed from the UFC roster. == Politics ==