| P | # | Player | Born | Height | Weight | Contract | |
|---|---|---|---|---|---|---|---|
| D | Florent Hanin | 1990-02-04 | 177 | 2017-06-30 | |||
| D | Mario Mutsch | 1984-09-03 | 173 | 74 | |||
| D | Yrondu Musavu-King | 1992-01-08 | 186 | 83 | 2020-06-30 | ||
| M | Nzuzi Toko | 1990-12-20 | 171 | 66 | 2020-06-30 | ||
| F | Albian Ajeti | 1997-02-26 | 182 | 76 | 2020-06-30 |
| Date | Player | From | To | Status | Src |
|---|---|---|---|---|---|
| 30.Jun | Yrondu Musavu-King (D) | FC St. Gallen | Udinese Calcio | Confirmed | |
| 30.Jun | Albian Ajeti (F) | FC St. Gallen | FC Augsburg | Confirmed | |
| 31.Aug | Albian Ajeti (F) | FC Augsburg | FC St. Gallen | Confirmed | |
| 30.Jun | Edgar Salli (F) | FC St. Gallen | AS Monaco FC | Confirmed | |
| 5.Jan | Florent Hanin (D) | Strømsgodset IF | FC St. Gallen | Confirmed | |
| 19.Aug | Edgar Salli (F) | AS Monaco FC | FC St. Gallen | Confirmed | |
| 1.Aug | Goran Karanovic (F) | FC St. Gallen | Angers SCO | Confirmed | |
| 21.Jul | Stéphane Besle (D) | FC St. Gallen | RC Lens | Confirmed | |
| 6.Jan | Ermir Lenjani (M) | FC St. Gallen | Stade Rennais FC | Confirmed | |
| 6.Feb | Mikael Ishak (F) | FC Köln | FC St. Gallen | Confirmed |