The Diocese of Cloyne has its beginnings in the monastic settlement of St. Colman at Cloyne in East Cork. A round tower and pre-reformation Cathedral still stand at this site.

Colman, son of Lenin, lived from 522 to 604 A.D. He had been a poet and bard at the court of Caomh, King of Munster at Cashel. It was St. Brendan of Clonfert that induced Colman to become Christian. He embraced his new faith eagerly and studied at the monastery of St. Jarleth in Tuam. He later preached in East Cork and established his own monastic settlement at Cloyne about 560 A.D. His feast day is celebrated on November 24th.

Cloyne was later to become the center of an extensive diocese in Munster. For eight centuries it was the residence of the Bishops of Cloyne and the setting for the Cathedral.

The troubled history of Ireland from the Norman to the Penal days was reflected in the affairs of the Church. The Diocese of Cloyne and Cork were united from 1429 to 1747. From 1747 to 1850 the Diocese of Cloyne and Ross were united. Since 1769 the Bishops of Cloyne, with the exception of Dr. Murphy, resided at Cobh (formerly Queenstown) on the north side of Cork Harbour. When the Diocese of Cloyne and Ross were separated in 1850 Bishop Keane planned a cathedral for Cobh to replace the inadequate parish Church of the time.

The years 1857 to 1867 were spent in planning the new project. The architects Pugin & Ashlin were chosen for the Cathedral and the result was one of the finest gems of neo-gothic architecture in Ireland. The building was completed in 1915. The Cathedral was consecrated by Bishop Brpwne on 12th. August 1919.

The Diocese is presently under the pastoral care of the Apostolic Administrator Archbishop Dermot Clifford. It stretches over most of the county of Cork, with the exception of the city and West Cork. Its 46 parishes run from Mitchelstown in the north-east to Rockchapel in the north-west, from Macroom in the south-west to Youghal in the south-east.