Leontios was born in Lemesos on March 9, 1896. He became a monk in 1913 and was ordained a deacon six years later. He studied at the University of Athens graduating in 1923. He did graduate studies in New York obtaining his Bachelors of Theology and his Masters in Sacred Theology. In 1930, while still in the US, he was elected Metropolitan of Paphos.
Leontios returned to Cyprus and was ordained a priest and a bishop so he could take over his duties. Upon the death of Cyril III, on November 16, 1933, he became caretaker of the Archbishopric throne of Cyprus.
Leontios fought the British colonial authorities for their intervention in the ecclesiastical matters of Cyprus. His adamant stand helped to reverse the 1937 laws concerning the election of archbishops in Cyprus. In November 1946, he was appointed to a delegation, sent to London and Athens, to seek the union of Cyprus with Greece. On June 20, 1947 he was elected Archbishop of Cyprus. In this capacity, he spoke on July 12, 1947 to the Cypriot people advising them to boycott the Advisory Council set up by the British. Two weeks later, on July 26, 1947, he died.