A protégé of Walter Goffart of the Toronto School of History, Gillett researches and teaches the field of Late Antiquity.
He received his BA in Australian Social History and Modern European History from the University of Queensland (1986), and an MA (1989) and PhD (1994) in Medieval Studies at the Centre for Medieval Studies of the University of Toronto.
His PhD was supervised by Walter Goffart, leader of the so-called Toronto School of History.
He is particularly interested in the role of communication in public life, and how the period of Late Antiquity has been constructed by modern historians.
Gillett is well known as the editor of the book On Barbarian Identity: Critical Approaches to Ethnicity in the Early Middle Ages (2002).