| Season | Team | Competition | MP | G | A | Rating | ||
|---|---|---|---|---|---|---|---|---|
| 2027 | Iceland U21 | Euro U21 - Qualification | 5 | 0 | 1 | 0 | 0 | – |
| 2025 | Iceland U21 | Friendly International | 3 | 0 | 0 | 0 | 0 | – |
| 2025 | Iceland U21 | Euro U21 - Qualification | 8 | 0 | 0 | 1 | 0 | – |
| 2024 | Iceland | Friendly International | 1 | 0 | 0 | 1 | 0 | – |
| 2023 | Iceland U21 | Friendly International | 1 | 0 | 0 | 0 | 0 | – |
| 2023 | Iceland U19 | Euro U19 | 3 | 0 | 0 | 0 | 0 | – |
| 2023 | Iceland U19 | Euro U19 - Qualification | 6 | 0 | 0 | 0 | 0 | – |
| 2022 | Iceland U18 | Friendly International | 2 | 0 | 0 | 0 | 0 | – |
| 2022 | Iceland U19 | Friendly International | 2 | 0 | 0 | 0 | 0 | – |
| 2022 | Iceland U19 | Euro U19 - Qualification | 4 | 0 | 0 | 0 | 0 | – |
| 2021 | Iceland U19 | Friendly International | 1 | 0 | 0 | 0 | 0 | – |
| 2020 | Iceland U17 | Friendly International | 1 | 0 | 0 | 0 | 0 | – |
| Total | 37 | 0 | 1 | 2 | 0 | – | ||
| Date | From | To | Type | |
|---|---|---|---|---|
| 07 Feb 2024 | Haugesund | Brommapojkarna | Transfer | |
| - | Valur | Haugesund | Transfer | |
| 02 Jul 2023 | Breidablik | Valur | Transfer | |
| - | Bologna | Breidablik | Return from loan | |
| 10 May 2020 | Breidablik | Bologna | Loan |
H. Karlsson career history shows progression across clubs and competitions, including club timeline, national team appearances and overall career totals.