| 1. Round | 01/03/2021 | Seongnam FC | - | Jeju United | 0:0 | ||||
| 2. Round | 06/03/2021 | Jeju United | - | Jeonbuk FC | 1:1 | ||||
| 3. Round | 09/03/2021 | Jeju United | - | Pohang Steelers | 1:0 | ||||
| 4. Round | 13/03/2021 | Daegu FC | - | Jeju United | 1:1 | ||||
| 5. Round | 16/03/2021 | Ulsan Hyundai FC | - | Jeju United | 0:0 | ||||
| 6. Round | 20/03/2021 | Jeju United | - | Gwangju FC | 1:1 | ||||
| 7. Round | 04/04/2021 | Suwon FC | - | Jeju United | 2:1 | ||||
| 8. Round | 07/04/2021 | Jeju United | - | Gangwon FC | 1:1 | ||||
| 12. Round | 24/04/2021 | Pohang Steelers | - | Jeju United | 0:0 | ||||
| 16. Round | 16/05/2021 | Jeju United | - | Daegu FC | 1:2 | ||||
| 17. Round | 19/05/2021 | Gwangju FC | - | Jeju United | 0:0 | ||||
| 19. Round | 29/05/2021 | Jeju United | - | Ulsan Hyundai FC | 1:2 | ||||
| 21. Round | 25/07/2021 | Gangwon FC | - | Jeju United | 2:2 | ||||
| 22. Round | 31/07/2021 | Jeju United | - | Incheon United | 1:4 | ||||
| 23. Round | 07/08/2021 | Suwon Bluewings | - | Jeju United | 0:0 | ||||
| 26. Round | 21/08/2021 | Suwon FC | - | Jeju United | 1:0 |
South Korea