| 3. Round | 16/09/2020 | TSV Steinbach Haiger | - | 1. FSV Mainz 05 II | 2:0 | ||||
| 6. Round | 30/09/2020 | 1. FSV Mainz 05 II | - | SSV Ulm 1846 | 1:1 | ||||
| 8. Round | 10/10/2020 | 1. FSV Mainz 05 II | - | VfB Stuttgart II | 1:0 | ||||
| 9. Round | 17/10/2020 | TSV Schott Mainz | - | 1. FSV Mainz 05 II | 3:0 | ||||
| 11. Round | 24/10/2020 | Hessen Kassel | - | 1. FSV Mainz 05 II | 2:1 | ||||
| 15. Round | 16/01/2021 | FSV Frankfurt | - | 1. FSV Mainz 05 II | 2:1 | ||||
| 16. Round | 19/01/2021 | 1. FSV Mainz 05 II | - | FC-Astoria Walldorf | 0:2 |  |
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| 17. Round | 23/01/2021 | VfR Aalen | - | 1. FSV Mainz 05 II | 1:2 | ||||
| 18. Round | 02/02/2021 | 1. FSV Mainz 05 II | - | FK Pirmasens | 1:2 | ||||
| 22. Round | 06/02/2021 | 1. FSV Mainz 05 II | - | 1899 Hoffenheim II | 0:1 | ||||
| 23. Round | 12/02/2021 | TSG Balingen | - | 1. FSV Mainz 05 II | 2:5 | ||||
| 25. Round | 28/02/2021 | SC Freiburg II | - | 1. FSV Mainz 05 II | 3:1 | ||||
| 26. Round | 06/03/2021 | 1. FSV Mainz 05 II | - | Bayern Alzenau | 2:1 | ||||
| 34. Round | 25/04/2021 | 1. FSV Mainz 05 II | - | SV 07 Elversberg | 1:5 | ||||
| 35. Round | 01/05/2021 | Rot-Weiß Koblenz | - | 1. FSV Mainz 05 II | 2:2 | ||||
| 37. Round | 08/05/2021 | FC-Astoria Walldorf | - | 1. FSV Mainz 05 II | 4:2 |
Belgium