The future ecclesiastic was born on February 12, 1845, in Constantinople as Simeon Izmirlian. He studied at local schools (Bezjian and Kum Kapu) and became a teacher at the St. Mary Church of Ortakeuy in 1862. After being ordained deacon, he was ordained a celibate priest (vartabed) with the name Mateos in 1869. Patriarch Mgrdich Khrimian noted his intellectual capability and turned him into his personal secretary. His impeccable credentials and active service earned him the rank of dzayrakuyn vartabed in 1873. He was elected primate of Balikesir in 1874 and two years later was consecrated bishop. In 1881 he published a voluminous book in Armenian (1300 pages), The Patriarchate of the Holy Armenian Apostolic Church and Aghtamar and Sis.
Izmirlian’s religious and political activities were at times inseparable from each other. In 1886-1890 he was primate of the diocese of Egypt, but had to resign for health reasons. He returned to his hometown, where he was ordained archbishop, and in December 1894 he was elected Patriarch of Constantinople. His activism in order to improve the situation of the Armenians in the provinces led him to constant clashes with the authorities. His tenure coincided with the Hamidian massacres of 1894-1896. His insistence on democratic reforms and Armenians rights, as well as his protest against the massacres earned him the title of “Iron Patriarch.” The Ottoman authorities tried to force him to present a letter that expressed his satisfaction with the situation, but Patriarch Izmirlian refused. Abdul Hamid II pressured him to abdicate, and in July 1896 he was exiled to Jerusalem for the next twelve years.
After the proclamation of the Ottoman Constitution (July 1908), Archbishop Mateos Izmirlian returned from his exile to Constantinople and was elected once again Patriarch after the resignation of Patriarch Maghakia Ormanian in October 1908. However, he did not remain in that position for long. Catholicos of All Armenians Mgrdich I Khrimian had passed away in October 1907. The National Ecclesiastical Assembly gathered in Holy Etchmiadzin elected Archbishop Mateos to replace Khrimian Hayrig in October 1908. The election was confirmed by a Russian imperial decree of April 15, 1909. The newly elected Catholicos departed from Constantinople in May. After introducing himself to Czar Nicholas II in St. Petersburg, he arrived in Etchmiadzin in June and was consecrated on September 13, 1909 as Mateos II.
Catholicos Mateos II would have a brief tenure of 15 months. He became the first Catholicos to make a pilgrimage to Ani, the ruined capital of medieval Armenia, by then within the Russian borders. His plan of action included the renewal of monastic life, the improvement of the Kevorkian Seminary, and the solution of various administrative issues.
The Catholicos passed away on December 11, 1910 and was buried in the courtyard of Holy Etchmiadzin. His correspondence was posthumously published in Cairo (1911).