He studied theology and philology at the University of Athens, After completing his studies (1872) he returned to Constantinople and was appointed professor at the Halki School of Theology. In 1879 he left to study in Germany , University of Munich, where he received his doctorate (1884). He returned and was appointed by Patriarch Joachim III as director of the Priestly School of Blachernae. In 1889 he was elected Metropolitan of Anchialos , which he served with excellence with Christian and humanistic virtues. He remained until 1906. He lived through the riots and the burning and destruction of Anchialos, (his great Library was burned) by the Exarchs. He was then sent to Cyprus as Patriarchal Exarch to settle matters of succession to the episcopal throne. Then (1909) he was appointed to the post of bishop of Cyprus. Bishop of Pelagonia and Nicosia. Unfortunately, it faced the terrible consequences of the Asia Minor disaster and experienced the drama of expatriation and population exchanges.

In 1925, Basil was elected vicar of the Patriarchal Ecumenical Throne, and a few months later the Holy Synod elected him Ecumenical Patriarch (13.7.1925).

Basil III was a courageous reformer and balancer in relations between the churches. We mention selectively the marriage of the clergy, the recognition of the Patriarchate of Romania, the assignment to the Church of Greece of the administration of the New Territories, and the change of the calendar. He left a rich body of theological writings.