Tupou played his junior rugby league for the Berala Bears and Guildford Owls before being signed by the Parramatta Eels.

On 30 September, he played for the Newtown Jets in their New South Wales Cup 22–16 Grand Final win over the Balmain Ryde-Eastwood Tigers.

On 12 October, Tupou played on the wing for Prime Minister's XIII in the 34–16 win over Papua New Guinea.

[17][18] Tupou made his international debut on the wing in the Kangaroos 30–12 loss against New Zealand at Suncorp Stadium, his only appearance in the tournament.

In Round 4 against cross-city rivals the South Sydney Rabbitohs, Tupou played his 100th NRL match and scored a try in the Roosters 20–6 win at ANZ Stadium.

He played wing in every game of their stunning charge to the 2017 Rugby League World Cup semi-finals.

On 30 September, Tupou played on the wing and scored the game's first try in Easts 21–6 victory over Melbourne in the 2018 NRL Grand Final.

[30] In round 2 of the 2019 NRL season, Tupou scored two tries as the Sydney Roosters defeated Manly-Warringah 26–18 at Brookvale Oval.

Tupou was involved in the match winning play late in the second half when he passed the ball on the inside to James Tedesco who raced away to score the deciding try.

[33] On 22 February, Tupou played for the Roosters in their 2020 World Club Challenge victory defeating St Helens 20–12.

Tupou played a total of 22 games as the club finished sixth on the table and reached the finals.

[45] In the second round of group matches at the 2021 Rugby League World Cup, Tupou scored a hat-trick in Tonga's 32–6 victory over Wales.

[47] In round 22 of the 2023 NRL season, Tupou became the Sydney Roosters record try scorer after he crossed over in the 70th minute of the clubs 32–10 loss against Brisbane at The Gabba.

[50] Tupou played 18 matches for the Sydney Roosters in the 2023 NRL season as the club finished 7th on the table and qualified for the finals.