He first attended Patrician Brothers' College, Blacktown and then transferred at the end of year 7 to The King's School, Parramatta.

In round 19 2021, Penisini made his NRL debut for Parramatta against the Canberra Raiders in a 12–10 loss at Cbus Super Stadium on the Gold Coast.

[6] In round 19 of the 2022 NRL season, Penisini was sent to the sin bin for a professional foul during Parramatta's 36–14 loss against Brisbane.

[8] In the third group game at the 2021 Rugby League World Cup, Penisini scored four tries in Tonga's 92-10 victory over the Cook Islands at the Riverside Stadium.

[11] In round 5 of the 2023 NRL season, Penisini was sent to the sin bin for a professional foul during Parramatta's 28-20 loss to the Sydney Roosters.