In round 10 of the 2016 NRL season, Gosiewski made his NRL debut for South Sydney against the Parramatta Eels.[6][7] He played a total of 5 games for South Sydney in 2016, for most of the season though, he featured for North Sydney, making 9 appearances and scoring 3 tries. In October, he re-signed with Souths on a one-year contract until the end of 2017.[8]
2017
Gosiewski spent most of the 2017 NRL season out with a torn patella.[9] After getting match fitness and game time with South Sydney's feeder club North Sydney, he was recalled to the South Sydney lineup and played his sole NRL game of the season in South Sydney's 36-18 victory over the New Zealand Warriors.[10] After not being offered a new contract by Souths, he signed a one-year contract in September, with the Manly-Warringah Sea Eagles starting in 2018.[11]
2018
Gosiewski made his debut for Manly in round 5 against the Gold Coast Titans. Gosiewski featured in 8 games for Manly as the club endured a torrid 2018 season finishing second last on the table.[12][13] Gosiewski resigned for the Manly Warringah Sea Eagles for another season, keeping him at the club until the end of 2019.
Gosiewski played 19 games for Manly in the 2019 NRL season as the club finished 6th on the table and qualified for the finals. Gosiewski played in both of Manly's finals matches and scored a try in the club's elimination final loss against South Sydney at ANZ Stadium.[15][16]
He played a total of 13 games for Manly-Warringah in the 2020 NRL season as they finished a disappointing 13th on the table.[18]
2021
Gosiewski played six games for Manly in the 2021 NRL season. On October 6, he was released by the Manly club. On October 15 Gosiewski signed a one-year deal with the St. George Illawarra Dragons for the 2022 season.[19]
2022
Gosiewski played four games for St. George Illawarra in the 2022 NRL season as the club finished 10th on the table and missed the finals.[20]
On 25 October, Gosiewski signed a one-year deal to join North Queensland starting in 2023.[21]
2023
Gosiewski was limited to only seven matches for North Queensland in the 2023 NRL season as the club finished 11th on the table.[22]
2024
On 29 March, Gosiewski asked North Queensland for an immediate release on compassionate grounds which was rejected by the club.[23]
On 29 April, Gosiewski was granted an immediate release from his North Queensland contract to join arch-rivals Brisbane until the end of 2025.[24]
He made six appearances for Brisbane in the 2024 NRL season which saw the club miss the finals finishing 12th on the table.[25]