His Eminence, Archbishop Dmitri was born Robert Royster to Protestant parents in a small Texas town on November 2, 1923. In 1941, at the age of 18, after intense study culminating in an interview with Greek Orthodox Archbishop [later Ecumenical Patriarch] Athenagoras he was received into the Orthodox Christian faith at Holy Trinity Greek Orthodox Church, Dallas, TX, whereupon he received the name Dmitri. His college studies at North Texas State University were interrupted when he entered the United States Army in 1943. After special training at the University of Michigan, he was commissioned as a Second Lieutenant and served as a Japanese language interpreter on the staff of General Douglas MacArthur in the Philippines and Japan.

Following military service, he completed his university education and became an instructor of Spanish language at Southern Methodist University, Dallas, where in 1949 he received a Master of Arts degree in Spanish and was named professor of Spanish literature. He was ordained to the diaconate and holy priesthood in November of 1954 by Bishop Bohdan of the Ukrainian Orthodox Diocese, after which he organized Saint Seraphim Orthodox Church, the first English-language parish in Dallas. He and his parish were received into the Metropolia, as the Orthodox Church in America was known at that time, in 1958.

During 1966, he attended Saint Vladimir's Seminary, New York, NY, and taught Spanish at Fordham University. In addition, he continued to serve as a pastor of Saint Seraphim Church until June 22, 1969, when he was consecrated to the episcopacy. Initially, he served as auxiliary to Archbishop John [Shahovskoy] of San Francisco and the West [1969-70] and as auxiliary to Metropolitan Ireney [1971-72]. In 1972, he was named ruling Bishop of the Diocese of Hartford and New England. In 1978, he was named ruling Bishop of the newly created Diocese of Dallas and the South, which comprised 14 states in the southern United States. He was charged with the development of the diocese, which at the time consisted of a few churches in Florida and Texas and several scattered missions. Saint Seraphim Church, Dallas, was designated the diocese's cathedral church, which meant that he was once again served as archpastor of the parish he had founded over two decades earlier. Under his leadership, the Diocese of the South has grown to well over 60 parishes and missions. In 1993, he was elevated to the dignity of Archbishop by the Holy Synod of Bishops.

In addition to his duties as ruling hierarch of the Diocese of the South, Archbishop Dmitri functions as Exarch for the Diocese of Mexico. He is well-known for his missionary efforts among Mexicans and Mexican-Americans, for whom he has translated Orthodox liturgical texts and theological works into Spanish. He is author of several theological books, including The Doctrine of Christ; Orthodox Christian Teaching: An Introduction to the Orthodox Faith; The Kingdom of God: The Sermon on the Mount; and The Parables of Christ, The Miracles of Christ. His latest work, published in 2003, is The Epistle to the Hebrews, A Commentary. At present, he is writing a Commentary on the Gospel According to St. Mark. He also has served as editor of the Diocese of the South's monthly newspaper, The Dawn, throughout its 25 years of existence.

On September 4, 2008, upon the retirement of Metropolitan Herman, the Holy Synod of the OCA named Archbishop Dmitri Locum Tenens of the Metropolitan See.