Watford U18: every transfer in and out, fees paid and earned, squad market value.
| Date | Player | From | To | Fee |
|---|---|---|---|---|
| 2023-07-19 | Jack Grieves | Watford U18 | Watford U21 | — |
| 2023-07-15 | Adrian Blake | Watford U18 | Utrecht U21 | Free |
| 2023-07-01 | Bogdan Marian | Watford U18 | FC Voluntari II | Free |
| 2023-02-14 | Bogdan Marian | Watford U18 | Rushden & Diam. | Loan |
| 2022-07-01 | Ryan Andrews | Watford U18 | Watford U21 | — |
| 2021-07-16 | Bosun Lawal | Watford U18 | Celtic B | — |
| 2021-07-01 | Jordan Harrison | Watford U18 | Watford U23 | — |
| 2021-07-01 | Bogdan Marian | Watford Yth. | Watford U18 | — |
| 2020-07-01 | Ryan Andrews | Watford Yth. | Watford U18 | — |
| 2020-07-01 | Jack Grieves | Without Club | Watford U18 | — |
| 2019-07-01 | Daniel Phillips | Watford U18 | Watford U23 | — |
| 2019-07-01 | Bosun Lawal | St. Kevins Boys | Watford U18 | — |
| 2019-03-18 | Jordan Harrison | Chelsea Youth | Watford U18 | — |
| 2018-11-01 | Jubril Adedeji | Watford U18 | HB Köge U19 | Free |
| 2018-08-24 | Giannis Sourdis | Watford U18 | Udinese U19 | Free |
| 2018-07-20 | Marian Huja | Watford U18 | HB Köge | — |
| 2017-07-01 | Jaime Alvarado | Watford U18 | Watford U23 | — |
| 2017-07-01 | Giannis Sourdis | PAO U17 | Watford U18 | Free |
| 2017-07-01 | Dion Pereira | Watford U18 | Watford U23 | — |
| 2017-07-01 | Andrew Thomas | Watford U18 | Stanford Card. | Free |