The Diocese of Galway is created on April 23, 1831. The diocese has its origins in the ancient Kilmacduagh monastery and the Wardenship of Galway (1484–1831). Following the abolition of the Wardenship by the Holy See in 1831, the first Bishop of the new Diocese of Galway is appointed in the same year.

In 1866, Bishop John McEvilly of Galway is made Apostolic Administrator of the diocese of Kilmacduagh and Kilfenora. When he is appointed coadjutor bishop to the Archdiocese of Tuam in 1878, he retains Galway until he succeeds as archbishop in 1881. McEvilly continues to oversee Kilmacduagh and Kilfenora until 1883 when Pope Leo XIII unites the diocese with the neighbouring Diocese of Kilmacduagh. At the same time, the ordinary of the United Diocese of Galway and Kilmacduagh is appointed, in perpetuum, as the Apostolic Administrator of the Diocese of Kilfenora.

The bishopric of Kilmacduagh had been a separate title until 1750 when Pope Benedict XIV decrees that it is to be united with the bishopric of Kilfenora. Since Kilmacduagh is in the Ecclesiastical province of Tuam while Kilfenora is in the Province of Cashel, it is arranged that the ordinary of the united dioceses is to be alternately bishop of one diocese and apostolic administrator of the other. The first holder of this unusual arrangement is Peter Kilkelly, who had been Bishop of Kilmacduagh since 1744. He becomes Apostolic Administrator of Kilfenora in September 1750. Since that date, Kilfenora has been administered by that united diocese as an apostolic vicariate. Since the territory of an apostolic vicariate comes directly under the pope as “universal bishop”, the pope exercises his authority in Kilfenora through a “vicar.”

The geographic remit of the see includes the city of Galway, parts of County Galway and the northern coastal part of County Clare. Large population centres include Ennistymon, Oranmore and Oughterard. The cathedral church of the diocese is the Cathedral of Our Lady Assumed into Heaven and St. Nicholas. It is in the ecclesiastical province of Tuam and is subject to the Metropolitan Archdiocese of Tuam. The deanery of Kilfenora, previously a diocese in its own right, lies in the ecclesiastical province of Cashel. The Ordinary is Bishop Brendan Kelly who is appointed on December 11, 2017.

(Pictured: The Cathedral of Our Lady Assumed into Heaven and St. Nicholas