| 01 Sept 17 | L. Rémy Loïc Rémy |  ChelseaCHE | → |  Las PalmasLPA | Undisclosed |
| 01 Sept 17 | L. Rémy Loïc Rémy | ChelseaCHE | → | Las PalmasLPA | Undisclosed |
| 31 Aug 17 | Kyle Jameson | ChelseaCHE | → |  West Bromwich AlbionWBA | Undisclosed |
| 31 Aug 17 | D. Zappacosta Davide Zappacosta |  TorinoTOR | → | ChelseaCHE | Undisclosed |
| 31 Aug 17 | D. Drinkwater Danny Drinkwater |  Leicester CityLEI | → | ChelseaCHE | Undisclosed |
| 31 Aug 17 | J. Houghton Jordan Houghton | ChelseaCHE | → |  Doncaster RoversDON | Loan |
| 31 Aug 17 | Kyle Jameson | ChelseaCHE | → | West Bromwich AlbionWBA | Loan |
| 31 Aug 17 | D. Zappacosta Davide Zappacosta | TorinoTOR | → | ChelseaCHE | Undisclosed |
| 31 Aug 17 | C. Wakefield Charlie Wakefield | ChelseaCHE | → |  StevenageSTE | Loan |
| 31 Aug 17 | Malakai Hinckson-Mars | ChelseaCHE | → |  BarnetBAR | Undisclosed |
| 28 Aug 17 | J. Boga Jeremie Boga | ChelseaCHE | → |  Birmingham CityBIR | Loan |
| 28 Aug 17 | J. Boga Jeremie Boga | ChelseaCHE | → | Birmingham CityBIR | Loan |
| 25 Aug 17 | K. Omeruo Kenneth Omeruo | ChelseaCHE | → |  KasimpasaKAS | Loan |
| 11 Aug 17 | L. Baker Lewis Baker | ChelseaCHE | → |  MiddlesbroughMID | Loan |
| 11 Aug 17 | L. Baker Lewis Baker | ChelseaCHE | → | MiddlesbroughMID | Loan |
| 02 Aug 17 | M. Pasalic Mario Pasalic | ChelseaCHE | → |  Spartak MoscowSPM | Loan |
| 31 Jul 17 | N. Matic Nemanja Matic | ChelseaCHE | → |  Manchester UnitedMAN | Undisclosed |
| 28 Jul 17 | M. Miazga Matt Miazga | ChelseaCHE | → |  VitesseVIT | Loan |
| 28 Jul 17 | M. Miazga Matt Miazga | ChelseaCHE | → | VitesseVIT | Loan |
| 27 Jul 17 | J. Blackman Jamal Blackman | ChelseaCHE | → |  Sheffield UnitedSHU | Loan |
| 27 Jul 17 | T. Kalas Tomás Kalas | ChelseaCHE | → |  FulhamFUL | Loan |
| 27 Jul 17 | M. Hector Michael Hector | ChelseaCHE | → |  Hull CityHUL | Loan |
| 27 Jul 17 | J. Blackman Jamal Blackman | ChelseaCHE | → | Sheffield UnitedSHU | Loan |
| 27 Jul 17 | T. Kalas Tomás Kalas | ChelseaCHE | → | FulhamFUL | Loan |
| 27 Jul 17 | M. Hector Michael Hector | ChelseaCHE | → | Hull CityHUL | Loan |
| 25 Jul 17 | I. Brown Isaiah Brown | ChelseaCHE | → |  Brighton & Hove AlbionBHA | Loan |
| 24 Jul 17 | M. Mount Mason Mount | ChelseaCHE | → | VitesseVIT | Loan |
| 24 Jul 17 | M. Mount Mason Mount | ChelseaCHE | → | VitesseVIT | Loan |
| 21 Jul 17 | J. Da Silva Jay Da Silva | ChelseaCHE | → |  Charlton AthleticCHA | Loan |
| 21 Jul 17 | Á. Morata Álvaro Morata |  Real MadridMAD | → | ChelseaCHE | Undisclosed |
| 21 Jul 17 | K. Zouma Kurt Zouma | ChelseaCHE | → |  Stoke CitySTK | Loan |
| 21 Jul 17 | Á. Morata Álvaro Morata | Real MadridMAD | → | ChelseaCHE | Undisclosed |
| 17 Jul 17 | I. Ugbo Ike Ugbo | ChelseaCHE | → |  BarnsleyBAR | Loan |
| 17 Jul 17 | M. Ali Mukhtar Ali | ChelseaCHE | → | VitesseVIT | Undisclosed |
| 17 Jul 17 | I. Ugbo Ike Ugbo | ChelseaCHE | → | BarnsleyBAR | Loan |
| 17 Jul 17 | M. Ali Mukhtar Ali | ChelseaCHE | → | VitesseVIT | Undisclosed |
| 16 Jul 17 | M. van Ginkel Marco van Ginkel | ChelseaCHE | → |  PSV EindhovenPSV | Loan |
| 16 Jul 17 | M. van Ginkel Marco van Ginkel | ChelseaCHE | → | PSV EindhovenPSV | Loan |
| 15 Jul 17 | T. Bakayoko Tiemoué Bakayoko |  AS MonacoMON | → | ChelseaCHE | Undisclosed |
| 15 Jul 17 | T. Bakayoko Tiemoué Bakayoko | AS MonacoMON | → | ChelseaCHE | Undisclosed |
| 13 Jul 17 | N. Chalobah Nathaniel Chalobah | ChelseaCHE | → |  WatfordWAT | Undisclosed |
| 12 Jul 17 | R. Loftus-Cheek Ruben Loftus-Cheek | ChelseaCHE | → |  Crystal PalaceCRY | Loan |
| 11 Jul 17 | O. Aina Ola Aina | ChelseaCHE | → | Hull CityHUL | Loan |
| 11 Jul 17 | O. Aina Ola Aina | ChelseaCHE | → | Hull CityHUL | Loan |
| 09 Jul 17 | A. Rüdiger Antonio Rüdiger |  AS RomaROMA | → | ChelseaCHE | Undisclosed |
| 09 Jul 17 | A. Rüdiger Antonio Rüdiger | AS RomaROMA | → | ChelseaCHE | Undisclosed |
| 07 Jul 17 | B. Collins Bradley Collins | ChelseaCHE | → |  Forest Green RoversFGR | Loan |
| 06 Jul 17 | C. Colkett Charlie Colkett | ChelseaCHE | → | VitesseVIT | Loan |
| 06 Jul 17 | C. Colkett Charlie Colkett | ChelseaCHE | → | VitesseVIT | Loan |
| 05 Jul 17 | T. Kane Todd Kane | ChelseaCHE | → |  FC GroningenGRO | Loan |
| 05 Jul 17 | T. Kane Todd Kane | ChelseaCHE | → | FC GroningenGRO | Loan |
| 04 Jul 17 | Kasey Palmer | ChelseaCHE | → |  Huddersfield TownHUD | Loan |
| 04 Jul 17 | T. Abraham Tammy Abraham | ChelseaCHE | → |  Swansea CitySWA | Loan |
| 03 Jul 17 | J. Terry John Terry | ChelseaCHE | → |  Aston VillaAVL | Free |
| 03 Jul 17 | J. Terry John Terry | ChelseaCHE | → | Aston VillaAVL | Free |
| 01 Jul 17 | W. Caballero Wilfredo Caballero |  Manchester CityMNC | → | ChelseaCHE | Free |
| 01 Jul 17 | F. Dabo Fankaty Dabo | ChelseaCHE | → | VitesseVIT | Loan |
| 01 Jul 17 | D. Solanke Dominic Solanke | ChelseaCHE | → |  LiverpoolLIV | Undisclosed |
| 01 Jul 17 | Billy Gilmour |  RangersRAN | → | ChelseaCHE | Undisclosed |
| 01 Jul 17 | A. Begovic Asmir Begovic | ChelseaCHE | → |  AFC BournemouthBOU | Undisclosed |
| 01 Jul 17 | C. Atsu Christian Atsu | ChelseaCHE | → |  Newcastle UnitedNEW | Undisclosed |
| 01 Jul 17 | E. Ampadu Ethan Ampadu |  Exeter CityEXE | → | ChelseaCHE | Undisclosed |
| 01 Jul 17 | N. Aké Nathan Aké | ChelseaCHE | → | AFC BournemouthBOU | Undisclosed |
| 01 Jul 17 | B. Traoré Bertrand Traoré | ChelseaCHE | → |  LyonLYON | 10000000 |
| 01 Jul 17 | J. Cuadrado Juan Cuadrado | ChelseaCHE | → |  JuventusJUV | 20000000 |
| 01 Jul 17 | C. Atsu Christian Atsu | ChelseaCHE | → | Newcastle UnitedNEW | Undisclosed |
| 01 Jul 17 | J. Cuadrado Juan Cuadrado | ChelseaCHE | → | JuventusJUV | 20000000 |
| 01 Jul 17 | B. Traoré Bertrand Traoré | ChelseaCHE | → | LyonLYON | 10000000 |
| 01 Jul 17 | Billy Gilmour | RangersRAN | → | ChelseaCHE | Undisclosed |
| 01 Jul 17 | F. Dabo Fankaty Dabo | ChelseaCHE | → | VitesseVIT | Loan |
| 24 May 17 | C. Atsu Christian Atsu | ChelseaCHE | → | Newcastle UnitedNEW | Undisclosed |
| 24 May 17 | C. Atsu Christian Atsu | ChelseaCHE | → | Newcastle UnitedNEW | Undisclosed |
| 01 Feb 17 | B. Ivanovic Branislav Ivanovic | ChelseaCHE | → |  Zenit St PetersburgZEN | Undisclosed |
| 29 Jan 17 | M. Ali Mukhtar Ali | ChelseaCHE | → | VitesseVIT | Loan |
| 29 Jan 17 | M. Ali Mukhtar Ali | ChelseaCHE | → | VitesseVIT | Loan |
| 27 Jan 17 | D. Conroy Dion Conroy | ChelseaCHE | → |  Swindon TownSWI | Undisclosed |
| 23 Jan 17 | F. Tomori Fikayo Tomori | ChelseaCHE | → | Brighton & Hove AlbionBHA | Loan |
| 23 Jan 17 | F. Tomori Fikayo Tomori | ChelseaCHE | → | Brighton & Hove AlbionBHA | Loan |
| 18 Jan 17 | P. Bamford Patrick Bamford | ChelseaCHE | → | MiddlesbroughMID | Undisclosed |
| 11 Jan 17 | I. Feruz Islam Feruz | ChelseaCHE | → | Swindon TownSWI | Loan |
| 11 Jan 17 | F. Dabo Fankaty Dabo | ChelseaCHE | → | Swindon TownSWI | Loan |
| 11 Jan 17 | C. Colkett Charlie Colkett | ChelseaCHE | → | Swindon TownSWI | Loan |
| 06 Jan 17 | I. Brown Isaiah Brown | ChelseaCHE | → | Huddersfield TownHUD | Loan |
| 06 Jan 17 | J. Mikel John Obi Mikel | ChelseaCHE | → |  Tianjin TigersTIG | Undisclosed |
| 06 Jan 17 | I. Brown Isaiah Brown | ChelseaCHE | → | Huddersfield TownHUD | Loan |
| 01 Jan 17 | J. Da Silva Jay Da Silva | ChelseaCHE | → | Charlton AthleticCHA | Loan |
| 01 Jan 17 | Oscar | ChelseaCHE | → |  Shanghai PortSIPG | Undisclosed |
| 01 Jan 17 | M. van Ginkel Marco van Ginkel | ChelseaCHE | → | PSV EindhovenPSV | Loan |
| 01 Jan 17 | M. van Ginkel Marco van Ginkel | ChelseaCHE | → | PSV EindhovenPSV | Loan |