Arahanga was born Julian Sonny Arahanga in Raetihi, Manawatū-Whanganui, New Zealand. Married to director Becs Arahanga https://www.imdb.com/name/nm8899761/. His father is screenwriter Larry Parr. Arahanga is 5 foot and 10 inches. His mother is a New Zealander of Estonian and Māori descent.

Of Māori descent, his family identifies with Ngāti Rangi and Atihaunui a Paparangi and is the half brother of Kiwi actor, Tammy Davis.

Arahanga is best known for his role in the movie Once Were Warriors from 1994, where he plays Nig Heke, Arahanga reprises his role in a sequel released in 1999.

He won a starring role in the Gregor Nicholas film Broken English, Released in 1996.

Later also in 1999, he starred in the action-sci fi movie The Matrix playing the role of Apoc.

• The Ferryman (2007) – Zane
• Eagle vs. Shark (2007) – Flight Extra
• Toy Boy (2004) – Angelo
• Fracture (2004) – Detective Harawira
• Forbidden Fury (2004)
• The Lost World (1999) (TV series) – Pintario
• The Matrix (1999) – Apoc
• What Becomes of the Broken Hearted? (1999) – Nig Heke
• Broken English (1996) – Eddie
• Hercules: The Legendary Journeys (1995–1996) (TV series) – Cassius (2 episodes)
• Once Were Warriors (1994) – Nig Heke
• The Makutu on Mrs Jones (1983) – Tawhai

• Julian Arahanga at IMDb
• Singing From the Inside Out – The Personal, the Public, The Private and The Penal: The Innovation Interview with Julian Arahanga, Ruia Aperahama and Evan Rhys Davies, July 2012