Watford U21: every transfer in and out, fees paid and earned, squad market value and €250k earned.
| Date | Player | From | To | Fee |
|---|---|---|---|---|
| 2024-07-24 | Jack Grieves | Watford U21 | Ross County | Loan |
| 2023-07-19 | Jack Grieves | Watford U18 | Watford U21 | — |
| 2023-07-01 | Ryan Andrews | Watford U21 | Watford | — |
| 2023-07-01 | Juergen Elitim | Watford U21 | Legia Warszawa | — |
| 2023-01-30 | Vincent Angelini | Watford U21 | Brentford B | — |
| 2022-08-10 | Daniel Phillips | Watford U21 | St. Johnstone | Free |
| 2022-07-26 | Derek Agyakwa | Watford U21 | Port Vale | Free |
| 2022-07-13 | Tiago Çukur | Watford U21 | Fenerbahçe | €250k |
| 2022-07-02 | Juergen Elitim | Watford U21 | Racing | Loan |
| 2022-07-01 | Ryan Andrews | Watford U18 | Watford U21 | — |
| 2022-07-01 | Jordan Harrison | Watford U21 | Without Club | — |
| 2022-01-13 | Jaime Alvarado | Watford U23 | Fortaleza CEIF | — |
| 2021-08-31 | Jaime Alvarado | Watford U23 | Racing Ferrol | Loan |
| 2021-07-28 | Sam Dalby | Watford U23 | Southend United | Free |
| 2021-07-23 | Daniel Phillips | Watford U23 | Gillingham FC | Loan |
| 2021-07-19 | Tiago Çukur | Watford U23 | Doncaster | Loan |
| 2021-07-14 | Vincent Angelini | Celtic U18 | Watford U23 | Free |
| 2021-07-09 | Juergen Elitim | Watford U23 | Dep. La Coruña | Loan |
| 2021-07-01 | Jordan Harrison | Watford U18 | Watford U23 | — |
| 2021-03-22 | Sam Dalby | Watford U23 | Woking | Loan |