Karekin II (secular name Ktrich G. Nersisian) was born on August 21, 1951, at the Voskehat village near Etchmiadzin, Armenia.
He attended the seminary in Etchmiadzin from 1965 to 1971. After graduation, he served as seminary assistant inspector and taught the New Testament.
He was ordained deacon in 1970 and priest with the name of Karekin in 1972.
In 1972, Catholicos Vasken I sent him to Vienna to continue his theological education and in 1975 to Germany to serve as pastor of the Armenian diaspora and to continue his theological education at Bonn University.
He returned to Etchmiadzin in 1979. Later he attended the post-graduate course at the Moscow Theological Academy of the Russian Orthodox Church. He was consecrated bishop in 1982 and elevated to the rank of archbishop in 1992. In 1980, he was appointed assistant chief vicar and in 1983 chief vicar of the Ararat patriarchal diocese.
In 1997, Catholicos Karekin I appointed him patriarchal locum tenens.
On October 27, 1999, the National Church Assembly of the Armenian Apostolic Church elected Karekin the 132nd Supreme Patriarch-Catholicos of All Armenians.
Karekin II is honorary member of the Armenian Academy of Sciences. He is holder of governmental awards from the USSR, Jordan, Romania, Ukraine and France.