| 1. Ronde | 01.03.2021 | Seongnam FC | - | Jeju United | 0:0 | ||||
| 2. Ronde | 06.03.2021 | Jeju United | - | Jeonbuk FC | 1:1 | ||||
| 3. Ronde | 09.03.2021 | Jeju United | - | Pohang Steelers | 1:0 | ||||
| 4. Ronde | 13.03.2021 | Daegu FC | - | Jeju United | 1:1 | ||||
| 5. Ronde | 16.03.2021 | Ulsan Hyundai FC | - | Jeju United | 0:0 | ||||
| 6. Ronde | 20.03.2021 | Jeju United | - | Gwangju FC | 1:1 | ||||
| 7. Ronde | 04.04.2021 | Suwon FC | - | Jeju United | 2:1 | ||||
| 8. Ronde | 07.04.2021 | Jeju United | - | Gangwon FC | 1:1 | ||||
| 12. Ronde | 24.04.2021 | Pohang Steelers | - | Jeju United | 0:0 | ||||
| 16. Ronde | 16.05.2021 | Jeju United | - | Daegu FC | 1:2 | ||||
| 17. Ronde | 19.05.2021 | Gwangju FC | - | Jeju United | 0:0 | ||||
| 19. Ronde | 29.05.2021 | Jeju United | - | Ulsan Hyundai FC | 1:2 | ||||
| 21. Ronde | 25.07.2021 | Gangwon FC | - | Jeju United | 2:2 | ||||
| 22. Ronde | 31.07.2021 | Jeju United | - | Incheon United | 1:4 | ||||
| 23. Ronde | 07.08.2021 | Suwon Bluewings | - | Jeju United | 0:0 | ||||
| 26. Ronde | 21.08.2021 | Suwon FC | - | Jeju United | 1:0 |
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