Marzello has been active on screen since 1976 in North America and Europe, his first role being in an episode of The Brothers. He has since appeared in productions that include The Spy Who Loved Me, Superman, Never Say Never Again, Pulaski, The Witches, Taggart, The House of Eliott, Dalziel and Pascoe, Little Britain, Nuclear Secrets and Mile High.

Marzello also lent his voice to the character of Fernando Ramirez in the UFO: Afterlight computer game.

He is married to the actress Lorelei King.