Sean O'Sullivan played six NRL matches and nine NSW Cup games after joining the Canterbury-Bankstown Bulldogs ahead of the 2026 season.
He had initially taken up an option for 2027, but he and the Bulldogs have since agreed to part ways.
The club released O'Sullivan from the final year of his contract so he could take up an opportunity with another club.
The Bulldogs wished O'Sullivan and his family all the best for the future.