In 1907 he was assigned as assistant to the Catholicossate in Mother See of Holy Etchmiadzin and elected Catholicos of All Armenians in December 1911, a post he held for three decades until 1930.

He presided over the Aid Committee for Armenian victims, refugees and wounded soldiers and their families.

He supported the various military campaigns, refusing to relocate the catholicosate from Etchmiadzin to a safer venue.

He was also actively involved in building new churches in the Armenian diaspora, developing a network of religious institutions and schools and for admitting the four-voice religious music of composer Makar Yekmalyan into the church Mass.

After his death, the Armenian Church as well as all organized religions in the Soviet Union became subject to persecution and rigid control, particularly through Joseph Stalin's orders.