Casey O'Neill has two losses against two opponents on her MMA record. For a list of O'Neill's best fights, refer to "Best fights of Casey O'Neill".
On December 16, 2023 Casey O'Neill faced off against Ariane Lipski in a flyweight bout at age 26. She was coming in with a record of 9-2 (4). O'Neill lost the fight via 2nd-round submission.
On March 18, 2023 Casey O'Neill faced off against Jennifer Maia in a flyweight bout at age 25. She was coming in with a record of 9-1 (4), and Maia was 34 years old and with a record of 20-9-1 (9). O'Neill lost the fight via 3-round unanimous decision.
