He launched his career at Mill & Mill Film in London as an offline editor. Upon returning to New Zealand, Marvyn took his first role at Weta Digital as a production coordinator on The Lord of the Rings: The Two Towers. He has added sixteen films to his credits during his time at Weta, including The Lord of the Rings: The Return of the King, King Kong, and Avatar.

Marvyn's recent credits include The Hobbit trilogy, and Independence Day: Resurgence. He recently finished producing Weta Digital's work on Avengers: Infinity War and Avengers: Endgame.