| Season | Team | Competition | MP | G | A | Rating | ||
|---|---|---|---|---|---|---|---|---|
| 2025 | Treaty United | Division 1 | 29 | 1 | 0 | 3 | 0 | – |
| 2024 | Galway | Premier Division | 17 | 0 | 2 | 2 | 1 | 6.6 |
| 2023 | Sligo Rovers | Premier Division | 4 | 0 | 0 | 1 | 0 | 6.4 |
| 2022 | Sligo Rovers | Premier Division | 29 | 3 | 0 | 3 | 0 | – |
| 2021 | Finn Harps | Premier Division | 32 | 4 | 0 | 8 | 0 | – |
| 2020 | Finn Harps | Premier Division | 14 | 2 | 0 | 4 | 0 | – |
| 2019 | Limerick | Division 1 | 25 | 2 | 0 | 5 | 0 | – |
| 2018 | Limerick | Premier Division | 27 | 1 | 0 | 3 | 0 | – |
| 2017 | Limerick | Premier Division | 1 | 0 | 0 | 1 | 0 | – |
| Total | 178 | 13 | 2 | 30 | 1 | – | ||
| Date | From | To | Type | |
|---|---|---|---|---|
| - | Treaty United | Heidelberg Utd | Free agent | |
| 02 Sept 2025 | Galway | Treaty United | Free agent | |
| 01 Apr 2024 | Sligo Rovers | Galway | Free agent | |
| 01 Jan 2022 | Finn Harps | Sligo Rovers | Free agent | |
| - | Limerick | Finn Harps | Free agent |
K. O'Sullivan career history shows progression across clubs and competitions, including club timeline, national team appearances and overall career totals.