| Temporada | Equipo | Competición | PJ | G | A | Nota | ||
|---|---|---|---|---|---|---|---|---|
| 2025/2026 | Morecambe | National League | 30 | 0 | 0 | 0 | 0 | – |
| 2024/2025 | Shrewsbury | League One | 27 | 0 | 0 | 1 | 0 | 6.8 |
| 2023/2024 | Burton | League One | 4 | 0 | 0 | 1 | 0 | 6.5 |
| 2022/2023 | Exeter | League One | 37 | 0 | 1 | 3 | 0 | 6.7 |
| 2021/2022 | Huddersfield | Championship | 1 | 0 | 0 | 0 | 0 | 7.3 |
| 2021 | Los Angeles FC | MLS | 8 | 0 | 0 | 0 | 0 | 6.9 |
| 2020/2021 | Rotherham | Championship | 26 | 0 | 0 | 1 | 0 | 6.8 |
| 2019/2020 | Bristol Rovers | League One | 8 | 0 | 0 | 0 | 0 | 6.8 |
| 2017/2018 | Sheffield Utd | Championship | 31 | 0 | 0 | 1 | 1 | 6.7 |
| 2016/2017 | Wycombe | League Two | 42 | 0 | 0 | 2 | 0 | – |
| 2016 | Ostersund | Allsvenskan | 12 | 0 | 0 | 0 | 0 | – |
| 2013/2014 | Chelsea U21 | Premier League U21 | 1 | 0 | 0 | 0 | 0 | – |
| Total | 227 | 0 | 1 | 9 | 1 | – | ||
| Fecha | Desde | Hacia | Tipo | |
|---|---|---|---|---|
| 10 sept 2025 | Shrewsbury | Morecambe | Free agent | |
| - | Burton | Shrewsbury | Transfer | |
| 07 mar 2023 | Exeter | Burton | Free agent | |
| - | Huddersfield | Exeter | Free agent | |
| - | Los Angeles FC | Huddersfield | Free agent | |
| 09 sept 2021 | Chelsea | Los Angeles FC | Free agent | |
| - | Rotherham | Chelsea | Return from loan | |
| - | Chelsea | Rotherham | Loan | |
| - | Bristol Rovers | Chelsea | Return from loan | |
| - | Chelsea | Bristol Rovers | Loan | |
| - | Vitesse | Chelsea | Return from loan | |
| 09 mar 2019 | Chelsea | Vitesse | Loan | |
| - | Leeds | Chelsea | Return from loan | |
| - | Chelsea | Leeds | Loan | |
| - | Sheffield Utd | Chelsea | Return from loan | |
| - | Chelsea | Sheffield Utd | Loan | |
| - | Wycombe | Chelsea | Return from loan | |
| - | Chelsea | Wycombe | Loan | |
| 06 dic 2016 | Ostersund | Chelsea | Return from loan | |
| - | Chelsea | Ostersund | Loan | |
| 01 may 2015 | Middlesbrough | Chelsea | Return from loan | |
| 09 ene 2014 | Chelsea | Middlesbrough | Loan |
J. Blackman career history shows progression across clubs and competitions, including club timeline, national team appearances and overall career totals.