Served as the Archbishop of Vancouver from 2009 until 2025. He had previously served as the coadjutor archbishop of Vancouver and as Secretary of the Congregation for Catholic Education. Prior to his appointment as bishop, he was a professor and academic administrator at the University of St. Thomas in Houston.

Born and raised in Ottawa, he completed his secondary education there before entering the Basilian novitiate after his first year of studies at St. Michael’s College in Toronto. He was ordained a priest in 1975. He later completed licentiate and doctoral degrees in dogmatic theology and began teaching at the University of St. Thomas.

After five years working in Rome at the Secretariat of State, he returned to the University of St. Thomas and became its president in 1997. In 2002, he was appointed Secretary of the Congregation for Catholic Education and was consecrated the following year. In 2007, he was named coadjutor archbishop of the Archdiocese of Vancouver before assuming the office of archbishop in 2009.

He currently serves on the Board of Directors of the University of St. Thomas, the Catholic Near East Welfare Association, and the editorial committee of the International Commission on English in the Liturgy.

Archbishop Emeritus Miller has published seven books and lectures and writes especially on the papacy and Catholic education. He has received seven honorary doctorates.