| 29 Aug 18 | F. Honorat Franck Honorat |  Saint-EtienneASSE | → |  Clermont FootCLER | Loan |
| 16 Aug 18 | R. Cabella Rémy Cabella |  MarseilleMAR | → | Saint-EtienneASSE | Undisclosed |
| 12 Aug 18 | O. Tannane Oussama Tannane | Saint-EtienneASSE | → |  FC UtrechtUTR | Loan |
| 12 Aug 18 | O. Tannane Oussama Tannane | Saint-EtienneASSE | → | FC UtrechtUTR | Loan |
| 10 Aug 18 | L. Lacroix Léo Lacroix | Saint-EtienneASSE | → |  Hamburg SVHSV | Loan |
| 01 Aug 18 | T. Kolodziejczak Timothée Kolodziejczak |  Tigres UANLUANL | → | Saint-EtienneASSE | Loan |
| 01 Aug 18 | T. Kolodziejczak Timothée Kolodziejczak | Tigres UANLUANL | → | Saint-EtienneASSE | Loan |
| 17 Jul 18 | W. Khazri Wahbi Khazri |  SunderlandSUN | → | Saint-EtienneASSE | Undisclosed |
| 09 Jul 18 | R. Pierre-Gabriel Ronael Pierre-Gabriel | Saint-EtienneASSE | → |  AS MonacoMON | Undisclosed |
| 06 Jul 18 | K. Théophile-Catherine Kévin Théophile-Catherine | Saint-EtienneASSE | → | DZXDinamo ZagrebDinamo Zagreb | Free |
| 02 Jul 18 | J. Bamba Jonathan Bamba | Saint-EtienneASSE | → |  LilleLILL | Free |
| 01 Jul 18 | V. Pajot Vincent Pajot | Saint-EtienneASSE | → |  AngersANG | Undisclosed |
| 01 Jul 18 | S. Janko Saidy Janko | Saint-EtienneASSE | → |  FC PortoPOR | Undisclosed |
| 01 Jul 18 | A. Maisonnial Anthony Maisonnial | Saint-EtienneASSE | → |  FC SionSION | Undisclosed |
| 01 Jul 18 | Jorginho | Saint-EtienneASSE | → | CSXCSKA SofiaCSKA Sofia | Loan |
| 01 Jul 18 | A. Katranis Alexandros Katranis | Saint-EtienneASSE | → |  MouscronREM | Loan |
| 31 Jan 18 | M. Debuchy Mathieu Debuchy |  ArsenalARS | → | Saint-EtienneASSE | Free |
| 31 Jan 18 | M. Debuchy Mathieu Debuchy | ArsenalARS | → | Saint-EtienneASSE | Free |
| 30 Jan 18 | B. Dabo Bryan Dabo | Saint-EtienneASSE | → |  FiorentinaFIO | Undisclosed |
| 30 Jan 18 | B. Dabo Bryan Dabo | Saint-EtienneASSE | → | FiorentinaFIO | Undisclosed |
| 25 Jan 18 | L. Diony Loïs Diony | Saint-EtienneASSE | → |  Bristol CityBRC | Loan |
| 25 Jan 18 | L. Diony Loïs Diony | Saint-EtienneASSE | → | Bristol CityBRC | Loan |
| 25 Jan 18 | N. Subotic Neven Subotic |  Borussia DortmundDOR | → | Saint-EtienneASSE | Undisclosed |
| 25 Jan 18 | N. Subotic Neven Subotic | Borussia DortmundDOR | → | Saint-EtienneASSE | Undisclosed |
| 18 Jan 18 | P. Ntep Paul-Georges Ntep |  VfL WolfsburgWOB | → | Saint-EtienneASSE | Loan |
| 18 Jan 18 | P. Ntep Paul-Georges Ntep | VfL WolfsburgWOB | → | Saint-EtienneASSE | Loan |
| 12 Jan 18 | Y. M'vila Yann M'vila |  Rubin KazanRUB | → | Saint-EtienneASSE | Free |