| 05 Oct 20 | D. Laxalt Diego Laxalt |  AC MilanMIL | → |  CelticCEL | Loan |
| 05 Oct 20 | D. Laxalt Diego Laxalt | AC MilanMIL | → | CelticCEL | Loan |
| 02 Sept 20 | S. Duffy Shane Duffy |  Brighton & Hove AlbionBHA | → | CelticCEL | Loan |
| 02 Sept 20 | S. Duffy Shane Duffy | Brighton & Hove AlbionBHA | → | CelticCEL | Loan |
| 28 Aug 20 | Barry Hepburn | CelticCEL | → |  Bayern MunichMUN | Undisclosed |
| 28 Aug 20 | Barry Hepburn | CelticCEL | → | Bayern MunichMUN | Undisclosed |
| 27 Aug 20 | D. Turnbull David Turnbull |  MotherwellMOT | → | CelticCEL | Undisclosed |
| 21 Aug 20 | J. Serrano Julien Serrano |  AS MonacoMON | → |  LivingstonLIV | Loan |
| 21 Aug 20 | J. Serrano Julien Serrano | AS MonacoMON | → | LivingstonLIV | Loan |
| 13 Aug 20 | A. Ajeti Albian Ajeti |  West Ham UnitedWHU | → | CelticCEL | Undisclosed |
| 13 Aug 20 | A. Ajeti Albian Ajeti | West Ham UnitedWHU | → | CelticCEL | Undisclosed |
| 31 Jul 20 | R. Edmondson Ryan Edmondson |  Leeds UnitedLEE | → |  AberdeenABER | Loan |
| 31 Jul 20 | R. Edmondson Ryan Edmondson | Leeds UnitedLEE | → | AberdeenABER | Loan |
| 30 Jul 20 | J. Eastwood Jake Eastwood |  Sheffield UnitedSHU | → |  KilmarnockKIL | Loan |
| 30 Jul 20 | J. Eastwood Jake Eastwood | Sheffield UnitedSHU | → | KilmarnockKIL | Loan |
| 28 Jul 20 | L. Bolton Luke Bolton |  Manchester CityMNC | → |  Dundee UnitedDUN | Loan |
| 28 Jul 20 | L. Bolton Luke Bolton | Manchester CityMNC | → | Dundee UnitedDUN | Loan |
| 24 Jul 20 | L. Balogun Leon Balogun |  Wigan AthleticWGA | → |  RangersRAN | Free |
| 24 Jul 20 | L. Balogun Leon Balogun | Wigan AthleticWGA | → | RangersRAN | Free |
| 17 Jul 20 | W. Foderingham Wes Foderingham | RangersRAN | → | Sheffield UnitedSHU | Free |
| 17 Jul 20 | W. Foderingham Wes Foderingham | RangersRAN | → | Sheffield UnitedSHU | Free |
| 08 Jul 20 | M. Polster Matt Polster | RangersRAN | → |  New England RevolutionNE | Undisclosed |
| 08 Jul 20 | M. Polster Matt Polster | RangersRAN | → | New England RevolutionNE | Undisclosed |
| 03 Jul 20 | M. Gillespie Mark Gillespie | MotherwellMOT | → |  Newcastle UnitedNEW | Free |
| 03 Jul 20 | M. Gillespie Mark Gillespie | MotherwellMOT | → | Newcastle UnitedNEW | Free |
| 01 Jul 20 | J. Defoe Jermain Defoe |  AFC BournemouthBOU | → | RangersRAN | Free |
| 01 Jul 20 | J. Defoe Jermain Defoe | AFC BournemouthBOU | → | RangersRAN | Free |
| 01 Jul 20 | M. Elyounoussi Mohammed Elyounoussi |  SouthamptonSOU | → | CelticCEL | Loan |
| 01 Jul 20 | M. Elyounoussi Mohammed Elyounoussi | SouthamptonSOU | → | CelticCEL | Loan |
| 31 Jan 20 | A. Jakubiak Alex Jakubiak |  WatfordWAT | → |  St MirrenSTM | Loan |
| 31 Jan 20 | A. Jakubiak Alex Jakubiak | WatfordWAT | → | St MirrenSTM | Loan |
| 31 Jan 20 | M. Butcher Matt Butcher | AFC BournemouthBOU | → |  St JohnstoneSTJO | Loan |
| 31 Jan 20 | R. Aarons Rolando Aarons | Newcastle UnitedNEW | → | MotherwellMOT | Loan |
| 31 Jan 20 | L. Morgan Lewis Morgan | CelticCEL | → |  Inter Miami CFMIA | Undisclosed |
| 31 Jan 20 | L. Morgan Lewis Morgan | CelticCEL | → | Inter Miami CFMIA | Undisclosed |
| 31 Jan 20 | M. Butcher Matt Butcher | AFC BournemouthBOU | → | St JohnstoneSTJO | Loan |
| 31 Jan 20 | R. Aarons Rolando Aarons | Newcastle UnitedNEW | → | MotherwellMOT | Loan |
| 22 Jan 20 | S. Woods Sam Woods |  Crystal PalaceCRY | → |  Hamilton AcademicalHAM | Loan |
| 22 Jan 20 | S. Woods Sam Woods | Crystal PalaceCRY | → | Hamilton AcademicalHAM | Loan |
| 22 Jan 20 | J. Hendry Jack Hendry | CelticCEL | → |  Melbourne City FCMCY | Loan |
| 22 Jan 20 | J. Hendry Jack Hendry | CelticCEL | → | Melbourne City FCMCY | Loan |
| 22 Jan 20 | S. Banks Scott Banks | Dundee UnitedDUN | → | Crystal PalaceCRY | Undisclosed |
| 13 Jan 20 | M. Ndjoli Mikael Ndjoli | AFC BournemouthBOU | → | MotherwellMOT | Loan |
| 13 Jan 20 | M. Ndjoli Mikael Ndjoli | AFC BournemouthBOU | → | MotherwellMOT | Loan |
| 08 Jan 20 | A. Famewo Akin Famewo |  Norwich CityNOR | → | St MirrenSTM | Loan |
| 08 Jan 20 | A. Famewo Akin Famewo | Norwich CityNOR | → | St MirrenSTM | Loan |