| 1. Round | 12/09/2020 | Walsall FC | - | Grimsby Town | 1:0 | ||||
| 2. Round | 19/09/2020 | Grimsby Town | - | Salford City | 0:4 |  |
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| 3. Round | 13/10/2020 | Cheltenham Town | - | Grimsby Town | 1:3 |  |
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| 7. Round | 20/10/2020 | Grimsby Town | - | Harrogate Town | 1:2 | |
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| 8. Round | 24/10/2020 | Grimsby Town | - | Carlisle United | 1:1 | ||||
| 9. Round | 27/10/2020 | Forest Green Rovers | - | Grimsby Town | 1:0 | ||||
| 10. Round | 31/10/2020 | Stevenage FC | - | Grimsby Town | 0:0 | ||||
| 17. Round | 12/12/2020 | Grimsby Town | - | Mansfield Town | 1:1 | ||||
| 18. Round | 15/12/2020 | Southend United | - | Grimsby Town | 3:1 | ||||
| 19. Round | 19/12/2020 | Grimsby Town | - | Scunthorpe United | 1:0 | ||||
| 4. Round | 22/12/2020 | Grimsby Town | - | Bradford City | 1:2 | ||||
| 20. Round | 26/12/2020 | Morecambe FC | - | Grimsby Town | 3:1 | ||||
| 21. Round | 29/12/2020 | Grimsby Town | - | Oldham Athletic | 0:0 | ||||
| 22. Round | 02/01/2021 | Grimsby Town | - | Cambridge United | 1:2 |
England