| P | # | Player | Born | Height | Weight | Contract | |
|---|---|---|---|---|---|---|---|
| GK | Artur Boruc | 1980-02-20 | 193 | 88 | 2018-06-30 | ||
| GK | David Marshall | 1985-03-15 | 190 | 82 | 2019-06-30 | ||
| D | Darren O'Dea | 1987-02-04 | 185 | 82 | |||
| D | Gary Caldwell | 1982-04-12 | 180 | 75 | 2014 jun | ||
| D | Jirí Jarosík | 1977-10-27 | 194 | 84 | |||
| D | Lee Naylor | 1980-03-19 | 175 | 71 | |||
| D | Scott Cuthbert | 1987-06-15 | 188 | 89 | |||
| M | Aiden McGeady | 1986-04-04 | 177 | 71 | 2020-06-30 | ||
| M | Evander Sno | 1987-04-09 | 189 | 84 | |||
| M | Paul Hartley | 1976-10-19 | 173 | 67 | 2011 | ||
| M | Ross Wallace | 1985-05-23 | 168 | 64 | 2015 jun | ||
| M | Shaun Maloney | 1983-01-24 | 170 | 70 | 2017-06-30 | ||
| M | Shunsuke Nakamura | 1978-06-24 | 178 | 69 | 2011 | ||
| M | Stiliyan Petrov | 1979-07-05 | 183 | 69 | Retired | ||
| M | Theódór Elmar Bjarnason | 1987-03-04 | 183 | 75 | 2017-06-30 | ||
| F | Cillian Sheridan | 1989-02-23 | 196 | 87 | |||
| F | Jan Vennegoor of Hesselink | 1978-11-07 | 188 | 85 | Retired | ||
| F | Kenny Miller | 1979-12-23 | 175 | 67 | |||
| F | Kjartan Finnbogason | 1986-07-09 | 188 | 82 | 2018-06-30 |
| Date | Player | From | To | Status | Src |
|---|---|---|---|---|---|
| 23.Apr | Kundai Benyu (M) | Helsingborgs IF | Celtic FC | Confirmed | |
| 27.Feb | Kundai Benyu (M) | Celtic FC | Helsingborgs IF | Confirmed | |
| 27.Feb | Kundai Benyu (M) | Ipswich Town | Celtic FC | Confirmed | |
| 30.Jun | Odsonne Edouard (F) | Celtic FC | Paris Saint-Germain F.C. | Confirmed | |
| 30.Jun | Patrick Roberts (M) | Celtic FC | Manchester City | Confirmed | |
| 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 |