Casey O'Neill

Casey O'Neill (born 7 October 1997) is a Scottish and Australian professional mixed martial artist. She currently competes in the women's Flyweight division of the Ultimate Fighting Championship (UFC).

Early life O'Neill was born in Irvine, Scotland and spent the early years of her life living in Kilmarnock. Her father, Cam, was a professional kickboxer and she began training in kickboxing at the age of four. At the age of 10 she moved with her family to Australia's Gold Coast where she attended Coombabah State High School. At the age of 13, O'Neill began training in other martial arts such as Brazilian jiu-jitsu.

Her father eventually relented and allowed O'Neill to compete in her first amateur MMA fight at the age of 15 where she was soundly beaten in the first round by an opponent four years her senior. She competed in another amateur fight the following year and was again defeated early in the first round. O'Neill then committed to honing her skills and spent the next two years training before returning to amateur circuit at 19 years of age. She then strung together five consecutive amateur wins before turning professional at 21 years of age. In 2019, O'Neill relocated to Phuket, Thailand to begin training at the renowned Tiger Muay Thai gym.

Mixed martial arts career Early career O'Neill made her professional debut against Amira Hafizović at the Eternal MMA 43 event on 5 April 2019 and was victorious via a unanimous decision. She then secured three more wins domestically against Jada Ketley, Miki Motono, in which she missed weight by 0.2 kg and was forced to vacate her title, and Caitlin McEwen before accepting her first fight overseas with the UAE Warriors promotion. In September 2020 she defeated Christina Stelliou via a second-round knockout at UAE Warriors 13.

Ultimate Fighting Championship In her UFC debut, O'Neill won with a second-round knockout victory over Shana Dobson at UFC Fight Night 185 on 20 February 2021.

O'Neill faced Lara Procópio on 19 June 2021 at UFC on ESPN 25. She won the bout after choking Procópio unconscious in the third round via rear-naked choke.

O'Neill faced Antonina Shevchenko on 2 October 2021 at UFC Fight Night 193. She won the fight via technical knockout in round two. This win earned her the Performance of the Night award.

O'Neill faced Roxanne Modafferi on 12 February 2022 at UFC 271. She won the fight via split decision. 19 out of 19 media outlets scored the fight for O'Neill. Judge Robert Alexander, who scored the fight 29-28 for Modafferi, received criticism for his scorecard. Michael Bisping, as part of the live commentary team for the broadcast, said "I don't think [Alexander] should be judging MMA. That judge does not know what he's looking at."

O'Neill was scheduled to face Jessica Eye on 2 July 2022 at UFC 276. However, O'Neill withdrew in late April due to torn ACL and was replaced by Maycee Barber.

O'Neill faced Jennifer Maia on 18 March 2023 at UFC 286. She lost the fight via unanimous decision.

O'Neill was scheduled to face Viviane Araújo on 9 September 2023 at UFC 293. However, O'Neill pulled out in early August due to injury and Araújo was rebooked for a new bout.

O'Neill faced Ariane Lipski on 16 December 2023 at UFC 296. She lost the fight via an armbar submission in the second round.

O'Neill was scheduled to face Tereza Bledá on 17 August 2024, at UFC 305. However, Bledá withdrew for unknown reasons and was replaced by Luana Santos. O'Neill defeated Santos by unanimous decision.

O'Neill faced Gabriella Fernandes on 28 March 2026 at UFC Fight Night 271. She won the fight by technical knockout in the first round.

O'Neill is scheduled face Eduarda Moura on 19 September 2026 at UFC 331.

Championships and accomplishments Mixed martial arts Ultimate Fighting Championship Performance of the Night (One time) Tied (Manon Fiorot, Carli Judice & Maycee Barber) for second most knockouts in UFC Women's Flyweight division history (3) Eternal MMA EMMA Strawweight Championship (One time) One successful title defense MMA Fighting 2021 Rookie of the Year

Mixed martial arts record Win

Gabriella Fernandes KO (punches) UFC Fight Night: Adesanya vs. Pyfer

Seattle, Washington, United States Win

Luana Santos Decision (unanimous) UFC 305

Perth, Australia Loss

Ariane Lipski Submission (armbar) UFC 296

Las Vegas, Nevada, United States Loss

Jennifer Maia Decision (unanimous) UFC 286

London, England Win

Roxanne Modafferi Decision (split) UFC 271

Houston, Texas, United States Win

Antonina Shevchenko TKO (punches) UFC Fight Night: Santos vs. Walker

Las Vegas, Nevada, United States Win

Lara Procópio Technical Submission (rear-naked choke) UFC on ESPN: The Korean Zombie vs. Ige

Las Vegas, Nevada, United States Win

Shana Dobson TKO (punches) UFC Fight Night: Blaydes vs. Lewis

Las Vegas, Nevada, United States Win

Christina Stelliou KO (punches) UAE Warriors 13

Abu Dhabi, United Arab Emirates Win

Caitlin McEwen Decision (unanimous) Eternal MMA 51

Perth, Australia Win

Miki Motono Decision (unanimous) Eternal MMA 48

Melbourne, Australia Win

Jada Ketley Submission (rear-naked choke) Eternal MMA 46

Melbourne, Australia Win

Amira Hafizović Decision (unanimous) Eternal MMA 43

Adelaide, Australia