| Season | Team | Competition | MP | G | A | Rating | ||
|---|---|---|---|---|---|---|---|---|
| 2025 | Akranes | Besta deild karla | 3 | 0 | 0 | 2 | 0 | – |
| 2024/2025 | Hvidovre IF | 1st Division | 20 | 0 | 0 | 3 | 0 | – |
| 2023/2024 | Hvidovre IF | Superliga | 27 | 0 | 1 | 8 | 0 | 6.7 |
| 2022/2023 | Horsens | Superliga | 28 | 1 | 0 | 4 | 0 | 6.6 |
| 2021/2022 | Horsens | 1st Division | 30 | 2 | 1 | 6 | 0 | – |
| 2020/2021 | Horsens | Superliga | 29 | 0 | 1 | 3 | 0 | 6.5 |
| 2019/2020 | Horsens | Superliga | 9 | 0 | 0 | 2 | 0 | 6.6 |
| 2016/2017 | Horsens | Superliga | 24 | 1 | 0 | 5 | 0 | – |
| 2015/2016 | Horsens | Bet25 Liga | 1 | 1 | 0 | 0 | 0 | – |
| 2015/2016 | Midtjylland | Superliga | 3 | 0 | 0 | 0 | 0 | – |
| 2013/2014 | Midtjylland | Superliga | 2 | 0 | 0 | 0 | 0 | – |
| Total | 176 | 5 | 3 | 33 | 0 | – | ||
| Date | From | To | Type | |
|---|---|---|---|---|
| - | Hvidovre IF | Akranes | Free agent | |
| - | Horsens | Hvidovre IF | ||
| 01 Apr 2020 | Kolding IF | Horsens | Return from loan | |
| - | Horsens | Kolding IF | Loan | |
| - | F. Amager | Horsens | Free agent | |
| 07 Jan 2017 | Midtjylland | F. Amager | ||
| - | Horsens | Midtjylland | Return from loan | |
| 07 Jan 2016 | Midtjylland | Horsens | Loan | |
| - | Horsens | Midtjylland | Return from loan | |
| - | Midtjylland | Horsens | Loan |
J. Gemmer career history shows progression across clubs and competitions, including club timeline, national team appearances and overall career totals.