Early years Mapapalangi played for the
South Sydney Rabbitohs'
Harold Matthews Cup team in 2018 and the
S. G. Ball Cup side in 2019. In 2020, he joined the
Manly Warringah Sea Eagles' S. G. Ball Cup team.
2022 Ahead of the 2022 season, Mapapalangi signed a 2-year contract to be a development player with the Knights'
NRL squad. In August, his contract was extended until the end of 2024 and upgraded into the top 30 squad. In round 23 of the
2022 NRL season, he made his NRL debut for the Knights against the
Canberra Raiders.
2025 On 2 April, Mapapalangi had signed a train and trial contract with the Wests Tigers.
2026 On 22 January,
Castleford Tigers announced the signing of Mapapalangi on a two-year deal. He made his debut against
Doncaster in the
Challenge Cup, and was named Tigers Man of the Match in the opening round defeat against
Wigan Warriors. In round 2, he scored his first try and provided an assist for his winger
Jason Qareqare against
Toulouse Olympique. Mapapalangi failed a head injury assessment against
St Helens in the cup, due to a late high tackle for which
Kyle Feldt received a three-match ban, and was thus ruled out for round 5. He provided three try assists for Qareqare against
Bradford Bulls in round 6, earning praise for a "sublime performance". After scoring two tries to lead Castleford to victory against Wigan in round 8, head coach
Ryan Carr reiterated his hope to agree a long-term contract with Mapapalangi. ==Statistics==