[3] Tupouniua made his first grade debut for the Sydney Roosters in round 16 of the 2018 NRL season against the Melbourne Storm at Adelaide Oval.

[8] He made a total of 20 appearances in the 2020 NRL season as the Sydney Roosters reached the finals but were eliminated by Canberra ending their quest for a third straight premiership.

In round 10 of the 2021 NRL season, he was sent to the sin bin for an illegal high tackle during the club's 30-16 victory over North Queensland.

[14][15] In round 18 of the 2022 NRL season, Tupouniua was taken from the field during the Sydney Roosters 54-26 victory over St. George Illawarra with a knee injury.

He played a total of 21 matches for the Sydney Roosters in the 2024 NRL season including their preliminary final loss against Melbourne.