Dr Barrett completed his medical training at the University of Newcastle following undergraduate studies in economics, and continued his prevocational training within Hunter New England Health.
Throughout his dermatology training, Dr Barrett worked at the Skin and Cancer Foundation, Westmead Children's Hospital, and the Royal Newcastle Centre. He has completed rural rotations throughout NSW including Lismore, Port Macquarie, Walgett, Dubbo, Orange, and with the Aboriginal Medical Service.