Hayes was originally a journalist who worked for a time in New York. He met director George Miller when he did the novelisation of the script to Mad Max (1979). He and Miller got on well and the director subsequently hired Hayes to help on the script for Mad Max 2 (1981). Hayes went on to become an in-house writer for Kennedy Miller, working on the scripts for all their subsequent mini-series. He also wrote the script for Dead Calm (1989).
His debut novel, I Am Pilgrim was published by Transworld Publishers on 18 July 2013. That same month, Metro-Goldwyn-Mayer acquired the film rights to the novel with Hayes attached to adapted it into a screenplay. He is also working on a stand-alone novel entitled The Year of the Locust.