Abp. Royster, who grew up in Texas and was raised as a Southern Baptist, converted to Orthodoxy in 1941. He entered North Texas State University but left in 1943 to join the Army. While in the Army he served as a Japanese language interpreter on the staff of General Douglas MacArthur in the Philippines and Japan. After leaving the Army he resumed his studies, eventually becoming a Spanish language instructor at Southern Methodist University. He received his Master of Arts in Spanish and became a Spanish literature professor.
In 1954, Abp. Royster was ordained to the priesthood, and served as the rector of St. Seraphim Orthodox Church in Dallas from then until 1969. On June 29, 1969, he was consecrated as Bishop of Berkeley (the Diocese of San Francisco and the West), making him the first Orthodox convert to be consecrated in America. In 1970, Bp. Dmitri was assigned as Bishop of Washington, auxiliary bishop to Metropolitan Ireney (Bekish). On October 19, 1971, Bp. Dmitri was elected Bishop of Hartford and New England.
In 1978, Bp. Dmitri became the first ruling bishop of the newly created Diocese of the South. He was elevated to the rank of archbishop in 1993.