Hexham has held a number of posts in various tertiary institutions of higher learning. He was an assistant professor at Bishop Lonsdale College, University of Derby, England from 1974–1977. He also served as a course tutor in the Open University at Derby (1975–77). Hexham then relocated to Canada and assumed the post of assistant professor at Regent College, Vancouver (1977–80). He became an assistant professor in religious studies at the University of Manitoba, Winnipeg (1980–84), and then an assistant professor in religious studies at the University of Calgary (1984–88). He was promoted to the rank of associate professor at Calgary (1988–92), and in 1992 assumed the post of Full Professor in religious studies.