Prast made his television debut in 1983 in the New Zealand drama series "Mortimer's Patch". In 1987 he returned to television, appearing as Alistair Redfern in the New Zealand soap opera "Gloss". In 1992 he starred in the drama movie about the French terrorist attack on a Greenpeace boat in Auckland Harbour in 1985. "The Sinking of the Rainbow Warrior" also starred Sam Neill and Jon Voight. He appeared as Nurse Paul Churchill on several episodes of the soap opera "Shortland Street" (1995–1996). Prast was a co-star in the 1998 New Zealand movie, "When Love Comes Along", with Rena Owen and Dean O'Gorman, directed by Garth Maxwell.