Fortuna Köln (3. Liga): every transfer in and out, fees paid and earned, and the market value of the squad. — spent, €440k earned. Record complete to 2026-09-01.
| Date | Player | From | To | Fee |
|---|---|---|---|---|
| 2026-09-01 | Jannik Mause | 1. FC Kaiserslautern | Fortuna Köln | Free |
| 2026-08-31 | Cedric Harenbrock | Hansa Rostock | Fortuna Köln | Free |
| 2026-08-31 | Dejan Galjen | Fortuna Köln | Eintracht Trier | Free |
| 2026-08-20 | Florian Heister | Alemannia Aachen | Fortuna Köln | Free |
| 2026-07-17 | Jasper Löffelsend | ŁKS Łódź | Fortuna Köln | Free |
| 2026-07-03 | Bennit Bröger | SC Paderborn 07 | Fortuna Köln | Loan |
| 2026-07-01 | David Savic | Fortuna Düsseldorf II | Fortuna Köln | Free |
| 2026-07-01 | Ben Zich | Fortuna Düsseldorf | Fortuna Köln | Free |
| 2026-07-01 | Romeo Aigbekaen | St. Pauli II | Fortuna Köln | Loan |
| 2026-07-01 | Kevin Krumme | SC Paderborn 07 U23 | Fortuna Köln | Loan |
| 2026-07-01 | Player | Fortuna Köln | Bonner SC | Free |
| 2026-02-02 | Dejan Galjen | Jahn Regensburg | Fortuna Köln | Free |
| 2026-01-06 | Neo Telle | 1.FC Köln | Fortuna Köln | Free |
| 2025-09-01 | Jonas Michelbrink | MSV Duisburg | Fortuna Köln | Free |
| 2025-08-14 | Player | Fortuna Köln | Eintracht Hohkeppel | Free |
| 2025-07-05 | Suheyel Najar | Viktoria Köln | Fortuna Köln | Free |
| 2025-07-01 | Timo Bornemann | Wuppertaler SV | Fortuna Köln | Free |
| 2025-07-01 | Georg Strauch | Köln II | Fortuna Köln | Free |
| 2025-07-01 | Tom Geerkens | VfB Lübeck | Fortuna Köln | Free |
| 2025-07-01 | K. Brechmann | Fortuna Düsseldorf II | Fortuna Köln | Free |