| 31 Aug 17 | C. Bryson Craig Bryson |  Derby CountyDER | → |  Cardiff CityCAR | Loan |
| 31 Aug 17 | D. John Declan John | Cardiff CityCAR | → |  RangersRAN | Loan |
| 31 Aug 17 | C. Noone Craig Noone | Cardiff CityCAR | → |  Bolton WanderersBOL | Undisclosed |
| 31 Aug 17 | S. O'Keefe Stuart O'Keefe | Cardiff CityCAR | → |  PortsmouthPOR | Loan |
| 31 Aug 17 | M. Kennedy Matthew Kennedy | Cardiff CityCAR | → | PortsmouthPOR | Loan |
| 31 Aug 17 | D. John Declan John | Cardiff CityCAR | → | RangersRAN | Loan |
| 31 Aug 17 | L. Feeney Liam Feeney |  Blackburn RoversBLK | → | Cardiff CityCAR | Loan |
| 25 Aug 17 | I. Meite Ibrahim Meite | Cardiff CityCAR | → |  Crawley TownCRA | Loan |
| 04 Aug 17 | B. Wilson Ben Wilson | Cardiff CityCAR | → |  Oldham AthleticOLD | Loan |
| 25 Jul 17 | I. Saadi Idriss Saadi | Cardiff CityCAR | → |  StrasbourgSTRA | Undisclosed |
| 25 Jul 17 | I. Saadi Idriss Saadi | Cardiff CityCAR | → | StrasbourgSTRA | Undisclosed |
| 13 Jul 17 | L. Tomlin Lee Tomlin |  Bristol CityBRC | → | Cardiff CityCAR | Undisclosed |
| 06 Jul 17 | L. Damour Loïc Damour |  Bourg-PeronnasFBBP | → | Cardiff CityCAR | Free |
| 01 Jul 17 | L. Camp Lee Camp |  Rotherham UnitedROT | → | Cardiff CityCAR | Free |
| 01 Jul 17 | S. Ajayi Semi Ajayi | Cardiff CityCAR | → | Rotherham UnitedROT | Undisclosed |
| 01 Jul 17 | T. Adeyemi Tom Adeyemi | Cardiff CityCAR | → |  Ipswich TownIPS | Free |
| 01 Jul 17 | N. Etheridge Neil Etheridge |  WalsallWAL | → | Cardiff CityCAR | Free |
| 01 Jul 17 | A. Le Fondre Adam Le Fondre | Cardiff CityCAR | → | Bolton WanderersBOL | Free |
| 01 Jul 17 | N. Mendez-Laing Nathaniel Mendez-Laing |  RochdaleROCH | → | Cardiff CityCAR | Free |
| 01 Jul 17 | C. Paterson Callum Paterson |  Heart of MidlothianHOM | → | Cardiff CityCAR | Free |
| 01 Jul 17 | C. Paterson Callum Paterson | Heart of MidlothianHOM | → | Cardiff CityCAR | Free |
| 28 Jun 17 | E. Huws Emyr Huws | Cardiff CityCAR | → | Ipswich TownIPS | Undisclosed |
| 23 Jun 17 | D. Ward Daniel Ward | Rotherham UnitedROT | → | Cardiff CityCAR | Undisclosed |
| 31 Jan 17 | A. Le Fondre Adam Le Fondre | Cardiff CityCAR | → | Bolton WanderersBOL | Loan |
| 31 Jan 17 | E. Huws Emyr Huws | Cardiff CityCAR | → | Ipswich TownIPS | Loan |
| 31 Jan 17 | M. Kennedy Matthew Kennedy | Cardiff CityCAR | → |  Plymouth ArgylePLY | Loan |
| 31 Jan 17 | S. O'Keefe Stuart O'Keefe | Cardiff CityCAR | → |  Milton Keynes DonsMKD | Loan |
| 30 Jan 17 | B. Wilson Ben Wilson | Cardiff CityCAR | → | RochdaleROCH | Loan |
| 30 Jan 17 | S. Ajayi Semi Ajayi | Cardiff CityCAR | → | Rotherham UnitedROT | Loan |
| 20 Jan 17 | T. O'Sullivan Tommy O'Sullivan | Cardiff CityCAR | → |  Colchester UnitedCOL | Undisclosed |
| 18 Jan 17 | Eli Phipps | Cardiff CityCAR | → | Colchester UnitedCOL | Undisclosed |
| 18 Jan 17 | A. McGregor Allan McGregor |  Hull CityHUL | → | Cardiff CityCAR | Loan |
| 18 Jan 17 | A. McGregor Allan McGregor | Hull CityHUL | → | Cardiff CityCAR | Loan |
| 13 Jan 17 | T. James Tom James | Cardiff CityCAR | → |  Yeovil TownYEO | Loan |
| 06 Jan 17 | I. Meite Ibrahim Meite | HBXHarrow BoroughHarrow Borough | → | Cardiff CityCAR | Undisclosed |
| 06 Jan 17 | G. Halford Greg Halford | Rotherham UnitedROT | → | Cardiff CityCAR | Undisclosed |
| 01 Jan 17 | D. Tutonda David Tutonda | Cardiff CityCAR | → |  BarnetBAR | Undisclosed |