 Urwin was born in Australia and attended Camberwell Grammar School in Melbourne.His sister is Kate Prowd, who also serves as a bishop in the Diocese of Melbourne; they are believed to be the only brother-sister bishops in the entire Anglican Communion.His brother is Michael Urwin, who was Headmaster of Brighton Grammar School, a prestigious HMC independent school, from 1996 to 2013, and now serves as the Registrar for the Diocese of Melbourne since 2019.