| P | # | Player | Born | Height | Weight | Contract | |
|---|---|---|---|---|---|---|---|
| GK | Logan Bailly | 1985-12-27 | 190 | 85 | |||
| D | Cristian Gamboa | 1989-10-24 | 173 | 67 | 2019-06-30 | ||
| D | Dedryck Boyata | 1990-11-28 | 188 | 76 | 2019-06-30 | ||
| D | Erik Sviatchenko | 1991-10-04 | 184 | 82 | 2020-06-30 | ||
| D | Kolo Touré | 1981-03-09 | 178 | 74 | 2017-06-30 | ||
| D | Mikael Lustig | 1986-12-13 | 189 | 77 | 2019-05-31 | ||
| M | Emilio Izaguirre | 1986-05-10 | 177 | 73 | 2017 jun | ||
| M | Kristoffer Ajer | 1998-04-17 | 196 | 84 | 2016-12-31 | ||
| M | Liam Henderson | 1996-04-25 | 183 | - | Loan | ||
| M | Olivier Ntcham | 1996-02-09 | 180 | 67 | 2021-06-30 | ||
| M | Patrick Roberts | 1997-02-05 | 167 | 58 | 2020-06-30 | ||
| M | Scott Sinclair | 1989-03-26 | 176 | 63 | 2020-06-30 | ||
| F | Colin Kazim-Richards | 1986-08-26 | 185 | 68 | 2018-06-30 | ||
| F | Leigh Griffiths | 1990-08-20 | 175 | 64 | 2017 dec | ||
| F | Moussa Dembélé | 1996-07-12 | 183 | 74 | |||
| F | Nadir Ciftci | 1992-02-12 | 183 | 77 | 2016-06-30 | ||
| F | Odsonne Edouard | 1998-01-16 | 187 | 83 | 2019-06-30 |
| Date | Player | From | To | Status | Src |
|---|---|---|---|---|---|
| 30.Jun | Scott Allan (M) | Rotherham United | Celtic FC | Confirmed | |
| 18.Jan | Mikael Lustig (D) | Celtic FC | Celtic FC | Extension | |
| 30.Aug | Cristian Gamboa (D) | West Bromwich Albion | Celtic FC | Confirmed | |
| 26.Aug | Stefan Johansen (M) | Celtic FC | Fulham FC | Confirmed | |
| 7.Aug | Scott Sinclair (M) | Aston Villa FC | Celtic FC | Confirmed | |
| 5.Aug | Scott Allan (M) | Celtic FC | Rotherham United | Confirmed | |
| 24.Jul | Kolo Touré (D) | Liverpool FC | Celtic FC | Confirmed | |
| 30.Jun | Nadir Ciftci (F) | Eskisehirspor | Celtic FC | Confirmed | |
| 28.Jun | Moussa Dembélé (F) | Fulham FC | Celtic FC | Confirmed | |
| 28.Jun | Stefan Scepovic (F) | Celtic FC | Getafe CF | Confirmed |