in 1972, he was chosen as the ninth bishop of toronto. in this capacity, he presided over a diocese of 160,000 people, the largest in canada. he became an archbishop in 1979. when the anglican diocese of toronto was divided into five regions in 1980, garnsworthy was given charge of the downtown division. garnsworthy was a frequent guest at official state functions, and in 1981 he conducted the funeral ceremonies for former premier john robarts.