1.FC Köln (Bundesliga): every transfer in and out, fees paid and earned, squad market value, €139m spent and €157m earned.
| Date | Player | From | To | Fee |
|---|---|---|---|---|
| 2026-07-01 | Tom Krauß | Mainz | 1.FC Köln | €3.5m |
| 2026-07-01 | Luca Kilian | 1.FC Köln | Without Club | — |
| 2026-07-01 | Jakub Kamiński | Wolfsburg | 1.FC Köln | €5.5m |
| 2026-07-01 | Florian Kainz | 1.FC Köln | Retired | — |
| 2026-07-01 | Eric Martel | 1.FC Köln | Mainz | Free |
| 2026-07-01 | Dominique Heintz | 1.FC Köln | Without Club | — |
| 2026-07-01 | Denis Huseinbasic | 1.FC Köln | Braga | Free |
| 2026-02-06 | Emin Kujovic | 1.FC Köln | Wolfsberger AC | Loan |
| 2026-02-02 | Felipe Chávez | FC Bayern II | 1.FC Köln | Loan |
| 2026-01-29 | Fynn Schenten | 1.FC Köln U19 | 1.FC Köln | — |
| 2026-01-14 | Chilohem Onuoha | 1.FC Köln | Estrela Amadora | Free |
| 2026-01-06 | Jahmai Simpson-Pusey | Man City U21 | 1.FC Köln | Loan |
| 2026-01-01 | Youssoupha Niang | 1.FC Köln II | 1.FC Köln | — |
| 2026-01-01 | Jusuf Gazibegovic | 1.FC Köln | Sturm Graz | Loan |
| 2025-09-01 | Jacob Christensen | 1.FC Köln | Molde FK | — |
| 2025-09-01 | Alessio Castro-Montes | Union SG | 1.FC Köln | €2m |
| 2025-08-28 | Leart Paçarada | 1.FC Köln | Heidenheim | — |
| 2025-08-13 | Rav van den Berg | Middlesbrough | 1.FC Köln | €8m |
| 2025-08-09 | Cenk Özkacar | Valencia | 1.FC Köln | Loan |
| 2025-08-05 | Kristoffer Lund | Palermo | 1.FC Köln | Loan |