| 2. Round | 06/03/2021 | Gwangju FC | - | Ulsan Hyundai FC | 0:1 | ||||
| 3. Round | 09/03/2021 | Ulsan Hyundai FC | - | Incheon United | 3:1 | ||||
| 4. Round | 13/03/2021 | Pohang Steelers | - | Ulsan Hyundai FC | 1:1 |  |
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| 7. Round | 03/04/2021 | Seongnam FC | - | Ulsan Hyundai FC | 0:1 | ||||
| 9. Round | 11/04/2021 | Suwon FC | - | Ulsan Hyundai FC | 0:1 | |
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| 10. Round | 18/04/2021 | Suwon Bluewings | - | Ulsan Hyundai FC | 3:0 | ||||
| 11. Round | 21/04/2021 | Ulsan Hyundai FC | - | Jeonbuk FC | 0:0 | |
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| 12. Round | 25/04/2021 | Incheon United | - | Ulsan Hyundai FC | 0:0 | ||||
| 16. Round | 16/05/2021 | Ulsan Hyundai FC | - | Suwon Bluewings | 1:1 | ||||
| 17. Round | 19/05/2021 | Jeonbuk FC | - | Ulsan Hyundai FC | 2:4 | ||||
| 14. Round | 20/06/2021 | Ulsan Hyundai FC | - | Seongnam FC | 2:2 | ||||
| 21. Round | 25/07/2021 | Ulsan Hyundai FC | - | Suwon FC | 2:5 | ||||
| 22. Round | 31/07/2021 | FC Seoul | - | Ulsan Hyundai FC | 0:0 | ||||
| 23. Round | 07/08/2021 | Ulsan Hyundai FC | - | Gangwon FC | 2:1 | ||||
| 26. Round | 22/08/2021 | Ulsan Hyundai FC | - | Suwon Bluewings | 3:1 | ||||
| 30. Round | 18/09/2021 | Daegu FC | - | Ulsan Hyundai FC | 2:1 | ||||
| 33. Round | 02/10/2021 | Suwon FC | - | Ulsan Hyundai FC | 0:3 |
South Korea