| 31 Aug 21 | C. Carter-Vickers Cameron Carter-Vickers |  Tottenham HotspurTOT | → |  CelticCEL | Loan |
| 31 Aug 21 | L. Dendoncker Lars Dendoncker |  Brighton & Hove AlbionBHA | → |  St JohnstoneSTJO | Loan |
| 31 Aug 21 | L. Dendoncker Lars Dendoncker | Brighton & Hove AlbionBHA | → | St JohnstoneSTJO | Loan |
| 31 Aug 21 | C. Carter-Vickers Cameron Carter-Vickers | Tottenham HotspurTOT | → | CelticCEL | Loan |
| 31 Aug 21 | O. Édouard Odsonne Édouard | CelticCEL | → |  Crystal PalaceCRY | Undisclosed |
| 31 Aug 21 | C. Ronan Connor Ronan |  Wolverhampton WanderersWOL | → |  St MirrenSTM | Loan |
| 31 Aug 21 | C. Ronan Connor Ronan | Wolverhampton WanderersWOL | → | St MirrenSTM | Loan |
| 31 Aug 21 | O. Édouard Odsonne Édouard | CelticCEL | → | Crystal PalaceCRY | Undisclosed |
| 27 Aug 21 | L. Hjelde Leo Fuhr Hjelde | CelticCEL | → |  Leeds UnitedLEE | Undisclosed |
| 27 Aug 21 | L. Hjelde Leo Fuhr Hjelde | CelticCEL | → | Leeds UnitedLEE | Undisclosed |
| 27 Aug 21 | M. Longstaff Matthew Longstaff |  Newcastle UnitedNEW | → |  AberdeenABER | Loan |
| 27 Aug 21 | M. Longstaff Matthew Longstaff | Newcastle UnitedNEW | → | AberdeenABER | Loan |
| 24 Aug 21 | A. Samuels Austin Samuels | Wolverhampton WanderersWOL | → | AberdeenABER | Loan |
| 24 Aug 21 | A. Samuels Austin Samuels | Wolverhampton WanderersWOL | → | AberdeenABER | Loan |
| 23 Aug 21 | B. Woodburn Ben Woodburn |  LiverpoolLIV | → |  Heart of MidlothianHOM | Loan |
| 23 Aug 21 | B. Woodburn Ben Woodburn | LiverpoolLIV | → | Heart of MidlothianHOM | Loan |
| 20 Aug 21 | D. Levitt Dylan Levitt |  Manchester UnitedMAN | → |  Dundee UnitedDUN | Loan |
| 20 Aug 21 | D. Levitt Dylan Levitt | Manchester UnitedMAN | → | Dundee UnitedDUN | Loan |
| 17 Aug 21 | J. Hungbo Joseph Hungbo |  WatfordWAT | → |  Ross CountyROSS | Loan |
| 17 Aug 21 | J. Hungbo Joseph Hungbo | WatfordWAT | → | Ross CountyROSS | Loan |
| 03 Aug 21 | J. Hart Joe Hart | Tottenham HotspurTOT | → | CelticCEL | Undisclosed |
| 03 Aug 21 | J. Hart Joe Hart | Tottenham HotspurTOT | → | CelticCEL | Undisclosed |
| 02 Aug 21 | H. Clarke Harrison Clarke |  ArsenalARS | → | Ross CountyROSS | Loan |
| 02 Aug 21 | H. Clarke Harrison Clarke | ArsenalARS | → | Ross CountyROSS | Loan |
| 29 Jul 21 | B. Baningime Beni Baningime |  EvertonEVE | → | Heart of MidlothianHOM | Undisclosed |
| 29 Jul 21 | B. Baningime Beni Baningime | EvertonEVE | → | Heart of MidlothianHOM | Undisclosed |
| 24 Jul 21 | C. Slattery Callum Slattery |  SouthamptonSOU | → |  MotherwellMOT | Undisclosed |
| 24 Jul 21 | C. Slattery Callum Slattery | SouthamptonSOU | → | MotherwellMOT | Undisclosed |
| 21 Jul 21 | K. Ajer Kristoffer Ajer | CelticCEL | → |  BrentfordBRE | Undisclosed |
| 21 Jul 21 | K. Ajer Kristoffer Ajer | CelticCEL | → | BrentfordBRE | Undisclosed |
| 14 Jul 21 | L. Abada Liel Abada |  Maccabi Petah-TikvaMPE | → | CelticCEL | Undisclosed |
| 09 Jul 21 | A. Awokoya-Mebude Adepapo Awokoya-Mebude |  RangersRAN | → | WatfordWAT | Free |
| 09 Jul 21 | A. Awokoya-Mebude Adepapo Awokoya-Mebude | RangersRAN | → | WatfordWAT | Free |
| 05 Jul 21 | A. Robertson Alex Robertson |  Manchester CityMNC | → | Ross CountyROSS | Loan |
| 05 Jul 21 | A. Robertson Alex Robertson | Manchester CityMNC | → | Ross CountyROSS | Loan |
| 02 Jul 21 | D. Barden Daniel Barden |  Norwich CityNOR | → |  LivingstonLIV | Loan |
| 02 Jul 21 | R. Devine Reece Devine | Manchester UnitedMAN | → | St JohnstoneSTJO | Loan |
| 02 Jul 21 | J. Vokins Jake Vokins | SouthamptonSOU | → | Ross CountyROSS | Loan |
| 02 Jul 21 | R. Devine Reece Devine | Manchester UnitedMAN | → | St JohnstoneSTJO | Loan |
| 02 Jul 21 | D. Barden Daniel Barden | Norwich CityNOR | → | LivingstonLIV | Loan |
| 02 Jul 21 | J. Vokins Jake Vokins | SouthamptonSOU | → | Ross CountyROSS | Loan |
| 01 Jul 21 | T. Jenks Teddy Jenks | Brighton & Hove AlbionBHA | → | AberdeenABER | Loan |
| 01 Jul 21 | A. Cochrane Alex Cochrane | Brighton & Hove AlbionBHA | → | Heart of MidlothianHOM | Loan |
| 01 Jul 21 | A. Cochrane Alex Cochrane | Brighton & Hove AlbionBHA | → | Heart of MidlothianHOM | Loan |
| 01 Jul 21 | T. Jenks Teddy Jenks | Brighton & Hove AlbionBHA | → | AberdeenABER | Loan |
| 01 Jul 21 | A. Lewis Adam Lewis | LiverpoolLIV | → | LivingstonLIV | Loan |
| 01 Jul 21 | A. Lewis Adam Lewis | LiverpoolLIV | → | LivingstonLIV | Loan |
| 28 Jun 21 | C. Ramirez Christian Ramirez |  Houston Dynamo FCHOU | → | AberdeenABER | Undisclosed |
| 28 Jun 21 | C. Ramirez Christian Ramirez | Houston Dynamo FCHOU | → | AberdeenABER | Undisclosed |
| 26 Apr 21 | M. Perez Manny Perez | CelticCEL | → |  Portland TimbersPOR | Undisclosed |
| 26 Apr 21 | M. Perez Manny Perez | CelticCEL | → | Portland TimbersPOR | Undisclosed |
| 22 Apr 21 | P. Klimala Patryk Klimala | CelticCEL | → |  New York Red BullsNY | Undisclosed |
| 22 Apr 21 | P. Klimala Patryk Klimala | CelticCEL | → | New York Red BullsNY | Undisclosed |
| 09 Mar 21 | A. Gutman Andrew Gutman | CelticCEL | → |  Atlanta United FCATL | Undisclosed |
| 09 Mar 21 | A. Gutman Andrew Gutman | CelticCEL | → | Atlanta United FCATL | Undisclosed |
| 05 Mar 21 | C. Harper Cameron Harper | CelticCEL | → | New York Red BullsNY | Undisclosed |
| 05 Mar 21 | C. Harper Cameron Harper | CelticCEL | → | New York Red BullsNY | Undisclosed |
| 18 Feb 21 | R. Hernández Ronald Hernández | AberdeenABER | → | Atlanta United FCATL | Loan |
| 18 Feb 21 | R. Hernández Ronald Hernández | AberdeenABER | → | Atlanta United FCATL | Loan |
| 18 Feb 21 | R. Hernández Ronald Hernández | AberdeenABER | → | Atlanta United FCATL | Loan |
| 18 Feb 21 | R. Hernández Ronald Hernández | AberdeenABER | → | Atlanta United FCATL | Loan |
| 01 Feb 21 | O. Ntcham Olivier Ntcham | CelticCEL | → |  MarseilleMAR | Loan |
| 01 Feb 21 | J. Kenny Jonjoe Kenny | EvertonEVE | → | CelticCEL | Loan |
| 01 Feb 21 | S. Edmundson Sam Edmundson | RangersRAN | → |  Derby CountyDER | Loan |
| 01 Feb 21 | O. Ntcham Olivier Ntcham | CelticCEL | → | MarseilleMAR | Loan |
| 01 Feb 21 | S. Edmundson Sam Edmundson | RangersRAN | → | Derby CountyDER | Loan |
| 01 Feb 21 | J. Kenny Jonjoe Kenny | EvertonEVE | → | CelticCEL | Loan |
| 15 Jan 21 | C. Cadden Christopher Cadden |  Columbus CrewCLB | → |  HibernianHIBS | Undisclosed |
| 15 Jan 21 | C. Cadden Christopher Cadden | Columbus CrewCLB | → | HibernianHIBS | Undisclosed |
| 12 Jan 21 | J. Irvine Jackson Irvine | XXX | → | HibernianHIBS | Free |
| 08 Jan 21 | G. Mackay-Steven Gary Mackay-Steven |  New York City FCNYC | → | Heart of MidlothianHOM | Free |
| 08 Jan 21 | M. Macey Matt Macey | ArsenalARS | → | HibernianHIBS | Free |
| 08 Jan 21 | M. Macey Matt Macey | ArsenalARS | → | HibernianHIBS | Free |