| 10 Sept 25 | L. Fabianski Lukasz Fabianski | XXX | → |  West Ham UnitedWHU | Free |
| 09 Sept 25 | W. Foderingham Wes Foderingham | West Ham UnitedWHU | → | ALXAris Limassol Aris Limassol | Undisclosed |
| 01 Sept 25 | N. Aguerd Nayef Aguerd | West Ham UnitedWHU | → |  MarseilleOLM | Undisclosed |
| 01 Sept 25 | Igor Julio |  Brighton & Hove AlbionBHA | → | West Ham UnitedWHU | Loan |
| 01 Sept 25 | J. Robinson Junior Robinson | West Ham UnitedWHU | → |  LivingstonLIV | Loan |
| 01 Sept 25 | M. Cornet Maxwel Cornet | West Ham UnitedWHU | → |  GenoaGEN | Loan |
| 01 Sept 25 | L. Orford Lewis Orford | West Ham UnitedWHU | → |  StevenageSTE | Loan |
| 01 Sept 25 | Emerson | West Ham UnitedWHU | → | MarseilleOLM | Undisclosed |
| 29 Aug 25 | M. Fernandes Mateus Fernandes |  SouthamptonSOU | → | West Ham UnitedWHU | Undisclosed |
| 29 Aug 25 | S. Magassa Soungoutou Magassa |  AS MonacoMON | → | West Ham UnitedWHU | Undisclosed |
| 23 Aug 25 | E. Álvarez Edson Álvarez | West Ham UnitedWHU | → |  FenerbahceFEN | Loan |
| 09 Aug 25 | M. Hermansen Mads Hermansen |  Leicester CityLEI | → | West Ham UnitedWHU | Undisclosed |
| 05 Aug 25 | V. Coufal Vladimír Coufal | West Ham UnitedWHU | → |  TSG HoffenheimTSG | Free |
| 04 Aug 25 | K. Casey Kaelan Casey | West Ham UnitedWHU | → |  Swansea CitySWA | Loan |
| 02 Aug 25 | C. Wilson Callum Wilson |  Newcastle UnitedNEW | → | West Ham UnitedWHU | Free |
| 25 Jul 25 | M. Forbes Michael Forbes | West Ham UnitedWHU | → |  Northampton TownNHT | Loan |
| 22 Jul 25 | G. Kodua Gideon Kodua | West Ham UnitedWHU | → |  Luton TownLTN | Loan |
| 20 Jul 25 | K. Walker-Peters Kyle Walker-Peters | SouthamptonSOU | → | West Ham UnitedWHU | Free |
| 15 Jul 25 | E. Diouf El Hadji Malick Diouf | SPXSlavia PragueSlavia Prague | → | West Ham UnitedWHU | Undisclosed |
| 10 Jul 25 | M. Kudus Mohammed Kudus | West Ham UnitedWHU | → |  Tottenham HotspurTOT | Undisclosed |
| 01 Jul 25 | J. Todibo Jean-Clair Todibo |  NiceNICE | → | West Ham UnitedWHU | Undisclosed |
| 03 Feb 25 | E. Ferguson Evan Ferguson | Brighton & Hove AlbionBHA | → | West Ham UnitedWHU | Loan |
| 31 Jan 25 | M. Forbes Michael Forbes | West Ham UnitedWHU | → |  Colchester UnitedCOL | Loan |