Spain: Tercera Division - Group 2 - Relegation Group |
| 10. Round | Club Siero | Vallobin | 2:3 (0:1, 2:2) | details | 06.06.2021 |
| 9. Round | Aviles Stadium | Club Siero | 0:2 (0:0, 0:2) | details | 29.05.2021 |
| 8. Round | Club Siero | Praviano | 3:3 | details | 23.05.2021 |
| 7. Round | SD Navarro CF | Club Siero | 2:1 (0:0, 2:1) | details | 16.05.2021 |
| 6. Round | Club Siero | Mosconia | 0:3 (0:1, 0:2) | details | 09.05.2021 |
| 5. Round | Vallobin | Club Siero | 2:0 (1:0, 1:0) | details | 02.05.2021 |
| 4. Round | Club Siero | Aviles Stadium | 0:2 (0:0, 0:2) | details | 25.04.2021 |
| 3. Round | Praviano | Club Siero | 1:0 (1:0, 0:0) | details | 18.04.2021 |
| 2. Round | Club Siero | SD Navarro CF | 1:4 (1:0, 0:4) | details | 11.04.2021 |
| 1. Round | Mosconia | Club Siero | 1:0 (0:0, 1:0) | details | 04.04.2021 |
Spain: Tercera Division - Group 2 - Main |
| Group B - 18. Round | L'Entregu | Club Siero | 7:0 (1:0, 6:0) | details | 28.03.2021 |
| Group B - 16. Round | Condal | Club Siero | 2:0 (2:0, 0:0) | details | 24.03.2021 |
| Group B - 15. Round | Club Siero | Basico Urraca | 0:1 (0:0, 0:1) | details | 21.03.2021 |
| Group B - 11. Round | Valdesoto | Club Siero | 1:1 (1:1, 0:0) | details | 17.03.2021 |
| Group B - 17. Round | Club Siero | Tuilla | 0:0 (0:0, 0:0) | details | 14.03.2021 |
| Group B - 10. Round | Club Siero | Llanes | 2:1 (1:1, 1:0) | details | 17.02.2021 |
| Group B - 14. Round | Real Titanico | Club Siero | 1:0 | details | 14.02.2021 |
| Group B - 13. Round | Club Siero | EI San Martin | 0:1 (0:0, 0:1) | details | 07.02.2021 |
| Group B - 12. Round | CD Colunga | Club Siero | 1:0 (0:0, 1:0) | details | 31.01.2021 |
| Group B - 9. Round | Club Siero | L'Entregu | 1:2 | details | 10.01.2021 |
| Group B - 5. Round | Club Siero | Real Titanico | 4:0 | details | 27.12.2020 |
| Group B - 4. Round | EI San Martin | Club Siero | 2:0 | details | 20.12.2020 |
| Group B - 8. Round | Tuilla | Club Siero | 2:0 (2:0, 0:0) | details | 13.12.2020 |
| Group B - 3. Round | Club Siero | CD Colunga | 0:1 (0:1, 0:0) | details | 08.12.2020 |
| Group B - 7. Round | Club Siero | Condal | 0:0 | details | 05.12.2020 |
| Group B - 6. Round | Basico Urraca | Club Siero | 0:2 | details | 29.11.2020 |
| Group B - 2. Round | Club Siero | Valdesoto | 0:1 | details | 15.11.2020 |
| Group B - 1. Round | Llanes | Club Siero | 0:2 | details | 18.10.2020 |
Spain: Tercera Division - Group 2 - Main |
| 38. Round | Club Siero | Caudal Deportivo | CAN. | details | 17.05.2020 |
| 37. Round | Condal | Club Siero | CAN. | details | 10.05.2020 |
| 36. Round | Club Siero | Covadonga | CAN. | details | 03.05.2020 |
| 35. Round | Llanes | Club Siero | CAN. | details | 26.04.2020 |
| 34. Round | Club Siero | Gijon Industrial | CAN. | details | 19.04.2020 |
| 33. Round | Real Aviles | Club Siero | CAN. | details | 12.04.2020 |
| 32. Round | Club Siero | L'Entregu | CAN. | details | 05.04.2020 |
| 31. Round | Llanera | Club Siero | CAN. | details | 29.03.2020 |
| 30. Round | Club Siero | CD Colunga | CAN. | details | 22.03.2020 |
| 29. Round | Club Siero | Mosconia | CAN. | details | 15.03.2020 |
| 28. Round | Lealtad | Club Siero | 0:0 (0:0, 0:0) | details | 07.03.2020 |
| 27. Round | Club Siero | Vallobin | 1:0 (1:0, 0:0) | details | 01.03.2020 |
| 26. Round | Basico Urraca | Club Siero | 4:1 | details | 23.02.2020 |
| 25. Round | Club Siero | Praviano | 2:3 (1:1, 1:2) | details | 16.02.2020 |
| 24. Round | Union Club Ceares | Club Siero | 0:0 (0:0, 0:0) | details | 08.02.2020 |
| 23. Round | Club Siero | SD Navarro CF | 1:3 | details | 02.02.2020 |
| 22. Round | Lenense | Club Siero | 1:1 (0:0, 1:1) | details | 26.01.2020 |
| 21. Round | Club Siero | EI San Martin | 1:1 (1:0, 0:1) | details | 19.01.2020 |
| 20. Round | Tuilla | Club Siero | 1:0 (1:0, 0:0) | details | 12.01.2020 |
| 19. Round | Caudal Deportivo | Club Siero | 1:0 (0:0, 1:0) | details | 04.01.2020 |
| 18. Round | Club Siero | Condal | 1:1 (0:0, 1:1) | details | 22.12.2019 |
| 17. Round | Covadonga | Club Siero | 3:3 | details | 15.12.2019 |