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. She began training under coach Daniel Doyle, and won two national championships by the age of 15. However, during that period Doyle was 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 move to Boston to train with Jimmy Pedro and his father.
Career
Judo
She changed weight classes in 2008, from the −63 kg division to the 78 kg division. However, she couldn't compete in the 2008 Summer Olympics as the United States had not qualified in that division. She won the Junior World Championship that year, and the following year placed second, becoming the first American to compete in two Junior World Championships finals. She won the gold medal in the −78 kg category at the World Judo Championships in 2010, the first American to do so since 1999. At the 2011 World Judo Championship 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, she 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. On August 31, 2016 the United States Judo Association made a batsugun promotion of Kayla to rokudan 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 will initially work as a commentator she also indicated she is contracted to fight, probably in the women's 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. Kayla Harrison was on the main card for PFL 11 in 2018 and defeated Moriel Charneski; 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. However 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 was forced to pull out of the bout. Genah Fabian was replaced by number 5 Bobbi Jo Dalziel. Kayla 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.
Television
Kayla Harrison has been a guest in episode 24 of season 6, and in episode 4 of season 7, of the television show "Impractical Jokers." She also appeared on an episode of “‘’Flea Market Flip’’” with her grandmother.
