| 31 Aug 18 | T. Abraham Tammy Abraham |  ChelseaCHE | → |  Aston VillaAVL | Loan |
| 31 Aug 18 | Michael Hector | ChelseaCHE | → |  Sheffield WednesdaySHW | Loan |
| 31 Aug 18 | T. Abraham Tammy Abraham | ChelseaCHE | → | Aston VillaAVL | Loan |
| 31 Aug 18 | Michael Hector | ChelseaCHE | → | Sheffield WednesdaySHW | Loan |
| 31 Aug 18 | Kylian Hazard | ChelseaCHE | → |  Club BruggeBRUG | Loan |
| 31 Aug 18 | B. Collins Bradley Collins | ChelseaCHE | → |  Burton AlbionBRT | Loan |
| 30 Aug 18 | I. Brown Isaiah Brown | ChelseaCHE | → |  Leeds UnitedLEE | Loan |
| 30 Aug 18 | I. Ugbo Ike Ugbo | ChelseaCHE | → |  Scunthorpe UnitedSCU | Loan |
| 30 Aug 18 | I. Brown Isaiah Brown | ChelseaCHE | → | Leeds UnitedLEE | Loan |
| 23 Aug 18 | T. Kalas Tomás Kalas | ChelseaCHE | → |  Bristol CityBRC | Loan |
| 23 Aug 18 | T. Kalas Tomás Kalas | ChelseaCHE | → | Bristol CityBRC | Loan |
| 15 Aug 18 | K. Omeruo Kenneth Omeruo | ChelseaCHE | → |  LeganésLEG | Loan |
| 15 Aug 18 | O. Aina Ola Aina | ChelseaCHE | → |  TorinoTOR | Loan |
| 15 Aug 18 | K. Omeruo Kenneth Omeruo | ChelseaCHE | → | LeganésLEG | Loan |
| 15 Aug 18 | O. Aina Ola Aina | ChelseaCHE | → | TorinoTOR | Loan |
| 14 Aug 18 | T. Bakayoko Tiemoué Bakayoko | ChelseaCHE | → |  AC MilanMIL | Loan |
| 14 Aug 18 | T. Bakayoko Tiemoué Bakayoko | ChelseaCHE | → | AC MilanMIL | Loan |
| 10 Aug 18 | J. Quintero Josimar Quintero | ChelseaCHE | → | LEXLleida EsportiuLleida Esportiu | Loan |
| 10 Aug 18 | M. Batshuayi Michy Batshuayi | ChelseaCHE | → |  ValenciaVAL | Loan |
| 10 Aug 18 | M. Batshuayi Michy Batshuayi | ChelseaCHE | → | ValenciaVAL | Loan |
| 09 Aug 18 | K. Zouma Kurt Zouma | ChelseaCHE | → |  EvertonEVE | Loan |
| 09 Aug 18 | J. Da Silva Jay Da Silva | ChelseaCHE | → | Bristol CityBRC | Loan |
| 09 Aug 18 | T. Courtois Thibaut Courtois | ChelseaCHE | → |  Real MadridMAD | Undisclosed |
| 09 Aug 18 | M. Kovacic Mateo Kovacic | Real MadridMAD | → | ChelseaCHE | Loan |
| 09 Aug 18 | T. Courtois Thibaut Courtois | ChelseaCHE | → | Real MadridMAD | Undisclosed |
| 09 Aug 18 | J. Da Silva Jay Da Silva | ChelseaCHE | → | Bristol CityBRC | Loan |
| 09 Aug 18 | M. Kovacic Mateo Kovacic | Real MadridMAD | → | ChelseaCHE | Loan |
| 08 Aug 18 | K. Arrizabalaga Kepa Arrizabalaga |  Athletic ClubATH | → | ChelseaCHE | Undisclosed |
| 08 Aug 18 | K. Arrizabalaga Kepa Arrizabalaga | Athletic ClubATH | → | ChelseaCHE | Undisclosed |
| 06 Aug 18 | M. Miazga Matt Miazga | ChelseaCHE | → |  NantesNANT | Loan |
| 06 Aug 18 | F. Tomori Fikayo Tomori | ChelseaCHE | → |  Derby CountyDER | Loan |
| 06 Aug 18 | F. Tomori Fikayo Tomori | ChelseaCHE | → | Derby CountyDER | Loan |
| 06 Aug 18 | M. Miazga Matt Miazga | ChelseaCHE | → | NantesNANT | Loan |
| 06 Aug 18 | K. Scott Kyle Scott | ChelseaCHE | → |  TelstarTEL | Loan |
| 30 Jul 18 | K. Palmer Kasey Palmer | ChelseaCHE | → |  Blackburn RoversBLK | Loan |
| 30 Jul 18 | K. Palmer Kasey Palmer | ChelseaCHE | → | Blackburn RoversBLK | Loan |
| 27 Jul 18 | V. Angban Victorien Angban | ChelseaCHE | → |  MetzMETZ | Loan |
| 26 Jul 18 | R. Green Robert Green |  Huddersfield TownHUD | → | ChelseaCHE | Free |
| 26 Jul 18 | J. Maddox Jacob Maddox | ChelseaCHE | → |  Cheltenham TownCHL | Loan |
| 25 Jul 18 | M. Pasalic Mario Pasalic | ChelseaCHE | → |  AtalantaATA | Loan |
| 25 Jul 18 | M. Pasalic Mario Pasalic | ChelseaCHE | → | AtalantaATA | Loan |
| 24 Jul 18 | Nathan | ChelseaCHE | → |  Atlético-MGCAM | Loan |
| 24 Jul 18 | Nathan | ChelseaCHE | → | Atlético-MGCAM | Loan |
| 21 Jul 18 | C. Colkett Charlie Colkett | ChelseaCHE | → |  Shrewsbury TownSHR | Loan |
| 21 Jul 18 | J. Boga Jeremie Boga | ChelseaCHE | → |  SassuoloSAS | Undisclosed |
| 21 Jul 18 | J. Boga Jeremie Boga | ChelseaCHE | → | SassuoloSAS | Undisclosed |
| 17 Jul 18 | T. Kane Todd Kane | ChelseaCHE | → |  Hull CityHUL | Loan |
| 17 Jul 18 | T. Kane Todd Kane | ChelseaCHE | → | Hull CityHUL | Loan |
| 17 Jul 18 | M. Mount Mason Mount | ChelseaCHE | → | Derby CountyDER | Loan |
| 17 Jul 18 | M. Mount Mason Mount | ChelseaCHE | → | Derby CountyDER | Loan |
| 16 Jul 18 | J. Blackman Jamal Blackman | ChelseaCHE | → | Leeds UnitedLEE | Loan |
| 16 Jul 18 | J. Blackman Jamal Blackman | ChelseaCHE | → | Leeds UnitedLEE | Loan |
| 14 Jul 18 | Jorginho |  NapoliNAP | → | ChelseaCHE | Undisclosed |
| 14 Jul 18 | Jorginho | NapoliNAP | → | ChelseaCHE | Undisclosed |
| 12 Jul 18 | Kenedy | ChelseaCHE | → |  Newcastle UnitedNEW | Loan |
| 12 Jul 18 | J. Rodríguez Joao Rodríguez | ChelseaCHE | → |  TenerifeTEN | Loan |
| 06 Jul 18 | Eduardo | ChelseaCHE | → |  VitesseVIT | Loan |
| 06 Jul 18 | Eduardo | ChelseaCHE | → | VitesseVIT | Loan |
| 05 Jul 18 | D. Pantic Danilo Pantic | ChelseaCHE | → | PBXPartizan BelgradePartizan Belgrade | Loan |
| 02 Jul 18 | J. Clark-Salter Jake Clark-Salter | ChelseaCHE | → | VitesseVIT | Loan |
| 02 Jul 18 | J. Clark-Salter Jake Clark-Salter | ChelseaCHE | → | VitesseVIT | Loan |
| 01 Jul 18 | N. Baxter Nathan Baxter | ChelseaCHE | → |  Yeovil TownYEO | Loan |
| 01 Jul 18 | L. Baker Lewis Baker | ChelseaCHE | → | Leeds UnitedLEE | Loan |
| 01 Jul 18 | J. Panzo Jonathan Panzo | ChelseaCHE | → |  AS MonacoMON | Free |
| 01 Jul 18 | Harvey St Clair | ChelseaCHE | → |  VeneziaVEN | Free |
| 01 Jul 18 | R. Sammut Ruben Sammut | ChelseaCHE | → |  FalkirkFALK | Loan |
| 01 Jul 18 | B. Rahman Baba Rahman | ChelseaCHE | → |  Schalke 04SCHA | Loan |
| 01 Jul 18 | R. James Reece James | ChelseaCHE | → |  Wigan AthleticWGA | Loan |
| 01 Jul 18 | T. Chalobah Trevoh Chalobah | ChelseaCHE | → |  Ipswich TownIPS | Loan |
| 01 Jul 18 | L. Baker Lewis Baker | ChelseaCHE | → | Leeds UnitedLEE | Loan |
| 01 Jul 18 | T. Chalobah Trevoh Chalobah | ChelseaCHE | → | Ipswich TownIPS | Loan |
| 01 Jul 18 | R. James Reece James | ChelseaCHE | → | Wigan AthleticWGA | Loan |
| 01 Jul 18 | B. Rahman Baba Rahman | ChelseaCHE | → | Schalke 04SCHA | Loan |
| 01 Jul 18 | J. Panzo Jonathan Panzo | ChelseaCHE | → | AS MonacoMON | Free |
| 01 Jul 18 | D. Sterling Dujon Sterling | ChelseaCHE | → |  Coventry CityCOV | Loan |
| 31 Jan 18 | K. Palmer Kasey Palmer | ChelseaCHE | → | Derby CountyDER | Loan |
| 31 Jan 18 | M. Batshuayi Michy Batshuayi | ChelseaCHE | → |  Borussia DortmundDOR | Loan |
| 31 Jan 18 | M. Batshuayi Michy Batshuayi | ChelseaCHE | → | Borussia DortmundDOR | Loan |
| 31 Jan 18 | K. Palmer Kasey Palmer | ChelseaCHE | → | Derby CountyDER | Loan |
| 31 Jan 18 | O. Giroud Olivier Giroud |  ArsenalARS | → | ChelseaCHE | Undisclosed |
| 31 Jan 18 | T. Kane Todd Kane | ChelseaCHE | → |  Oxford UnitedOXF | Loan |
| 30 Jan 18 | Emerson |  AS RomaROMA | → | ChelseaCHE | Undisclosed |
| 30 Jan 18 | Emerson | AS RomaROMA | → | ChelseaCHE | Undisclosed |
| 29 Jan 18 | B. Rahman Baba Rahman | ChelseaCHE | → | Schalke 04SCHA | Loan |
| 29 Jan 18 | C. Musonda Charly Musonda | ChelseaCHE | → |  CelticCEL | Loan |
| 29 Jan 18 | B. Rahman Baba Rahman | ChelseaCHE | → | Schalke 04SCHA | Loan |
| 29 Jan 18 | C. Musonda Charly Musonda | ChelseaCHE | → | CelticCEL | Loan |
| 23 Jan 18 | Kenedy | ChelseaCHE | → | Newcastle UnitedNEW | Loan |
| 08 Jan 18 | J. Clark-Salter Jake Clark-Salter | ChelseaCHE | → |  SunderlandSUN | Loan |
| 08 Jan 18 | J. Clark-Salter Jake Clark-Salter | ChelseaCHE | → | SunderlandSUN | Loan |
| 05 Jan 18 | R. Barkley Ross Barkley | EvertonEVE | → | ChelseaCHE | Undisclosed |
| 04 Jan 18 | I. Ugbo Ike Ugbo | ChelseaCHE | → |  Milton Keynes DonsMKD | Loan |
| 01 Jan 18 | D. Costa Diego Costa | ChelseaCHE | → |  Atletico MadridATL | Undisclosed |
| 01 Jan 18 | D. Costa Diego Costa | ChelseaCHE | → | Atletico MadridATL | Undisclosed |