Graham Oppy was born in Benalla in 1960 to a Methodist family, but he ceased to be a religious believer as a young teenager. His family moved to Ballarat in 1965 and had his secondary schooling at Wesley College, Melbourne. He attended Melbourne University from 1979, where he completed two degrees: a BA in philosophy and a B.Sc in mathematics. In 1987 he started graduate work at Princeton University under the supervision of Gilbert Harman on questions in the philosophy of language.

He was a lecturer at the University of Wollongong from 1990—1992 and after doing a post-doc at the Australian National University, he came to Monash as a senior lecturer, and was promoted to Professor in 2005. He is currently Associate Dean of Research (since 2004) and Associate Dean of Graduate Studies in the Faculty of Arts at Monash University. He currently has three children; Alfred Oppy, Calvin Oppy and Gilbert Oppy.