Abp. Kyrill was born Boris Mikhailovich Dmitriev (Борис Михайлович Дмитриев) on November 24, 1954 in San Francisco, California. At the age of 18, he was tonsured reader by Archbishop Anthony (Medvedev). In 1976 he graduated from University with a degree in theology. He then attended Saint Vladimir's Seminary, where he received his masters degree.
In 1981 he was tonsured a monk and ordained a hierodeacon and then a hieromonk by Metropolitan Philaret (Voznesensky). The same year he was appointed to the Russian Ecclesiastic Mission in Jerusalem as a teacher of Russian and English at the Bethany School. In 1982 he was transferred to the Western American diocese.
After the repose of Archbishop Anthony in 2000, he was appointed ruling hierarch of the Western American Diocese.
In 2003 he was elevated to the rank of archbishop. The same year he participated in the first official delegation of the Russian Orthodox Church Outside Russia to Russia, which opened the process of reconciliation with the Moscow Patriarchate.