| 2. Round | 25/10/2020 | Athletic Club B | - | Racing Santander | 0:1 | ||||
| 3. Round | 01/11/2020 | Club Portugalete | - | Athletic Club B | 2:3 | ||||
| 4. Round | 07/11/2020 | Athletic Club B | - | SD Amorebieta | 2:1 | ||||
| 5. Round | 14/11/2020 | Athletic Club B | - | CD Alavés B | 2:0 | ||||
| 9. Round | 03/01/2021 | Athletic Club B | - | Barakaldo CF | 3:0 | ||||
| 12. Round | 16/01/2021 | Athletic Club B | - | Arenas de Getxo | 1:1 | ||||
| 13. Round | 24/01/2021 | Racing Santander | - | Athletic Club B | 1:1 | ||||
| 14. Round | 30/01/2021 | Athletic Club B | - | Club Portugalete | 2:0 | ||||
| 15. Round | 06/02/2021 | SD Amorebieta | - | Athletic Club B | 2:3 | ||||
| 19. Round | 06/03/2021 | Athletic Club B | - | CD Laredo | 2:1 | ||||
| 20. Round | 14/03/2021 | Barakaldo CF | - | Athletic Club B | 3:1 | ||||
| 17. Round | 17/03/2021 | Athletic Club B | - | SD Leioa | 4:0 | ||||
| 22. Round | 28/03/2021 | Real Unión | - | Athletic Club B | 0:1 |
Spain