His Holiness Karekin II (secular name Ktritch) was born in 1951 in the village of Voskehat near Etchmiadzin. There he attended elementary school. In 1965 he was admitted to the Theological Academy of St. Etchmiadzin and graduated in 1971 with distinction. After completing his studies at the Theological Academy, he was appointed assistant to the Rector of the Academy and taught the "New Testament".
In 1972 he was ordained a celibate priest by Archbishop Diran Nersoyan and given the spiritual name Karekin. In the same year he was sent to Vienna by Catholicos Wasken I for further training. In 1975 he was appointed pastor of the Armenian community in Germany. At the same time he continued his theology studies at the University of Bonn. In 1979 he returned to Armenia and was immediately sent by the Catholicos to Zagorsk to study at the Russian Orthodox Academy there.
In 1980 Father Karekin was appointed Deputy Vicar Bishop of the Diocese of Ararat and in 1983 he became Vicar General of this important diocese. In October of the same year he received episcopal ordination and in 1992 the dignity and title of Archbishop.
In 1989, Archbishop Karekin Nersisyan founded the Waskenyan Seminary at Lake Sevan, which came under the Diocese of Ararat.
In 1990 he opened a "Christian Education Center" in his diocese, which provides religious instruction in 56 schools in the district of the diocese of Ararat. In 1992, thanks to the efforts of Archbishop Karekin Nersisyan, three of the pioneer palaces were converted into youth centers where thousands of youth received spiritual education.
Since 1990, Archbishop Nersisyan has been a member of the Supreme Spiritual Council (central executive body) of the Church of Armenia.
In 1995 Archbishop Karekin Nersisyan stood as a candidate in the election of the new Catholicos. On the third ballot he withdrew his candidacy in favor of the Catholicos of the House of Cilicia, HH Karekin II.
In 1998 he was appointed his deputy by the Catholicos Karekin I. When Catholicos Karekin I died in June 1999, the National Ecclesiastical Assembly elected him On 04.11. In the same year his consecration and anointing as Catholicos of All Armenians took place in the Cathedral of St. Etchmiadzin.