He previously played for the Wests Tigers, South Sydney Rabbitohs and New Zealand Warriors in the National Rugby League.

[2] Sironen played his junior rugby league for the Holy Cross Rhinos, before being signed by the Wests Tigers.

[10] On September 5, Sironen signed a one-year deal to join South Sydney for the 2019 season after failing to secure a first grade spot with Wests.

[13] In round 7 of the 2020 NRL season, Sironen scored his first try in the top grade as South Sydney were defeated by Penrith 20–12 at Bankwest Stadium.

[17] Sironen played 19 games for New Zealand in the 2021 NRL season where the club finished 12th on the table and missed the finals.