Semisi Paea was born in Tonga and raised in Rotorua, New Zealand.

He played junior rugby for Ngongotaha Rugby Club and Rotorua Boys High School.

Paea made his test debut for the ‘Ikale Tahi against the Cook Islands in a World Cup Qualifier match in 2021. He was also included in the Tonga team for the Pacific Nations Cup in July of 2021, playing against Samoa and Australia A. Paea later the Bay of Plenty Steamers for the 2021 NPC season. His great form earned him selection for the New Zealand Barbarians.

At the end of 2022, Paea signed with the New England Free jacks in Major League Rugby and made 13 appearances for the side.

Paea was a standout in the World Rugby 2022 Pacific Combine Program and was named the most promising player, earning him an opportunity with the Moana Pasifika development side. In 2024 he made his Super Rugby Pacific debut off the bench for Moana Pasifika in their match against the Brumbies in Round 5.

In 2025 Paea levelled up with some starting opportunities for Moana Pasifika, showcasing his athleticism and high work rate.

Moana Pasifika debut: 2024 v ACT Brumbies