A native of Christchurch, New Zealand, Warbeck became involved in local theatre there, which led to him receiving a scholarship to attend the Royal Academy of Dramatic Art in London in 1965. After attending for four terms, Warbeck dropped out and began working as a model. He made his feature film debut in John Hough's "" (1969), reuniting with the director again for 1971's "Twins of Evil". Throughout the 1970s, Warbeck appeared in numerous international exploitation films, including "A Fistful of Dynamite" (1971) and "Black Snake" (1974), which established him as a niche action film star.