| P | # | Player | Born | Height | Weight | Contract | |
|---|---|---|---|---|---|---|---|
| D | Ludvig Öhman Silwerfeldt | 1991-10-04 | 189 | 82 | 2021-06-30 |
| Date | Player | From | To | Status | Src |
|---|---|---|---|---|---|
| 9.Mar | Moses Ogbu (F) | Grimsby Town | Mjällby AIF | Confirmed | |
| 8.Jan | Sebastian Ring (D) | Grimsby Town | Kalmar FF | Confirmed | |
| 8.Jan | Ludvig Öhman Silwerfeldt (D) | IF Brommapojkarna | Grimsby Town | Confirmed | |
| 28.Dec | Sebastian Ring (D) | Örebro SK | Grimsby Town | Confirmed | |
| 23.Nov | Robert Eagle (M) | Grimsby Town | Alfreton Town | Confirmed | |
| 28.Sep | Andrew Wright (M) | Scunthorpe United | Grimsby Town | Confirmed | |
| 23.Sep | Danny Carlton (F) | Bury FC | Grimsby Town | Confirmed | |
| 31.Aug | Richard O'Donnell (GK) | Sheffield Wednesday | Grimsby Town | Confirmed | |
| 31.Aug | Nick Hegarty (M) | Grimsby Town | St Mirren | Confirmed | |
| 1.Aug | Matt Heywood (D) | Grimsby Town | Barrow | Confirmed |