Kayla Jean Harrison (born July 2, 1990) is an American professional mixed martial artist and former judoka. She currently competes in the women's Bantamweight division of the Ultimate Fighting Championship (UFC), where she is the current UFC Women's Bantamweight Champion. She is the first female fighter to win an Olympic gold medal and a UFC championship. She is also a former two-time Professional Fighters League lightweight champion. As of November 18, 2025, she is #2 in the UFC women's pound-for-pound rankings.
In judo, Harrison won the women’s 78 kg gold medal in the 2010 World Judo Championships and gold medals at the 2012 and 2016 Summer Olympics. She remains the only American judoka to have won a gold medal in Judo at the Summer Olympics and one of a rare few to have won a gold medal in the World Judo Championships. In 2016, she was promoted to Rokudan (6th-degree black belt) by the United States Judo Association, becoming the youngest ever to achieve the rank.
After making her MMA debut in 2018, Harrison won the PFL Lightweight World Tournament in 2019 and successfully repeated as champion in 2021. She signed with the UFC in January 2024, defeating former champion Holly Holm in her promotional debut. In June 2025, she captured the UFC Bantamweight Championship via second-round kimura submission of Julianna Peña.
Harrison was inducted into the Martial Arts History Museum Hall of Fame in 2012, the United States Judo Federation Hall of Fame in 2015, and the International Sports Hall of Fame in March 2023.
Born in Middletown, Ohio, Harrison took up judo at the age of six, having been introduced to the sport by her mother, who was a black belt. She graduated from Middletown High School (Ohio).
She began training under coach Daniel Doyle, and won two national championships by the age of 15. During that period, Doyle was sexually abusing Harrison, who reported it to another judoka, who in turn told Harrison's mother. She subsequently reported this to the police. Doyle was convicted and sentenced to a ten-year prison term. A month after the abuse was revealed, she moved away from her home in Ohio to Boston to train with Jimmy Pedro and his father.
Harrison changed weight classes in 2008, from the –63 kg division to the –78 kg division. She could not compete in the 2008 Summer Olympics as the United States had not qualified in that division. She won the 2008 Junior World Championship that year, and the following year placed second, becoming the first American to compete in two Junior World Championships finals.
Harrison won the gold medal in the –78 kg category at the 2010 World Championships, the first American to do so since 1999 (when her coach, Jimmy Pedro, did so in Birmingham, United Kingdom). At the 2011 World Championships in Paris, she placed third taking the bronze medal. Harrison had lost to the eventual winner, Audrey Tcheuméo of France, in her semi-final.
Prior to the 2012 Summer Olympics in London, Harrison was injured during training, having torn a medial collateral ligament. On August 2, 2012, she won the Olympic title in the –78 kg category, defeating Gemma Gibbons of Britain by two yukos, to become the first American to win an Olympic gold medal in judo. She earned a second Olympic gold medal in the same weight class in 2016 in Rio, defeating Audrey Tcheuméo of France.
In 2015, Harrison was elected to the United States Judo Federation Hall Of Fame and on August 31, 2016, following her second Olympic gold medal, the United States Judo Association promoted Harrison to rokudan (6th Degree Black Belt) making her the youngest person in the US to ever be awarded this rank.
Harrison, a former training partner of fellow judoka Ronda Rousey, announced in October 2016 that she had signed with World Series of Fighting. While she would initially work as a commentator she also indicated she was contracted to fight, in the women's 145 pounds (66 kg) division.
Harrison made her MMA debut at PFL 2 on June 21, 2018, against Brittney Elkin in the Women's Lightweight division. She won via submission due to an armbar in the first round.
For her second professional fight, Harrison faced Jozette Cotton at PFL 6 on August 16, 2018. She won the fight via TKO in the third round.
Harrison was on the main card for PFL 11 in 2018 and defeated Moriel Charneski via first-round TKO; after her victory, it appeared that she was not completely content with her own performance.
Harrison was expected to headline the first event of PFL's second season against Svetlana Khautova on May 9, 2019. Khautova withdrew from the bout and was replaced by Larissa Pacheco. Harrison won the fight by unanimous decision.
Harrison faced Morgan Frier in the co-main event of PFL 4 on July 11, 2019. She won the fight by key lock submission in the first round. Subsequently, Harrison signed a new long-term contract extension with the PFL.
After becoming second in the preliminary round standing, Harrison secured a position at the playoffs. She was originally scheduled to face number 3 ranked Genah Fabian at PFL 7 on October 11, 2019, but Fabian was forced to pull out of the bout. Fabian was replaced by number 5 Bobbi Jo Dalziel. Harrison would win the fight by an armbar in the first round.
Harrison faced Larissa Pacheco in rematch for the Women's Lightweight final at PFL 10 on December 31, 2019. After dominating every round with her superior grappling, Harrison won the fight by unanimous decision to win the 2019 Women's Lightweight Championship.