| 2026-09-19 | UFC 331: Van vs. Pantoja 2 | Women’s Flyweight | Casey O'Neill def. Eduarda Moura | Submission (armbar) | 1 | 3:22 |
| 2026-03-28 | UFC Fight Night: Adesanya vs. Pyfer | Women’s Flyweight | Casey O'Neill def. Gabriella Fernandes | KO (punches) | 1 | 3:11 |
| 2024-08-18 | UFC 305: du Plessis vs. Adesanya | Women’s Flyweight | Casey O'Neill def. Luana Santos | Decision (unanimous) (30–27, 30–27, 30–26) | 3 | 5:00 |
| 2023-12-16 | UFC 296: Edwards vs. Covington | Women’s Flyweight | Ariane Lipski def. Casey O'Neill | Submission (armbar) | 2 | 1:18 |
| 2023-03-18 | UFC 286: Edwards vs. Usman 3 | Women’s Flyweight | Jennifer Maia def. Casey O'Neill | Decision (unanimous) (30–27, 29–28, 29–28) | 3 | 5:00 |
| 2022-02-12 | UFC 271: Adesanya vs. Whittaker 2 | Women’s Flyweight | Casey O'Neill def. Roxanne Modafferi | Decision (split) (29–28, 28–29, 29–28) | 3 | 5:00 |
| 2021-10-02 | UFC Fight Night: Santos vs. Walker | Women’s Flyweight | Casey O'Neill def. Antonina Shevchenko | TKO (punches) | 2 | 4:47 |
| 2021-06-19 | UFC on ESPN: The Korean Zombie vs. Ige | Women’s Flyweight | Casey O'Neill def. Lara Procópio | Technical Submission (rear-naked choke) | 3 | 2:54 |
| 2021-02-20 | UFC Fight Night: Blaydes vs. Lewis | Women’s Flyweight | Casey O'Neill def. Shana Dobson | TKO (punches) | 2 | 3:41 |