In 1842 Rome subdivided the vast diocese of Sydney thereby creating the diocese of Adelaide and Bishop Francis Murphy (1842-1858) was appointed as the first Bishop of Adelaide and consecrated in Sydney on 8th September 1844.

Adelaide remained remained a Suffragan Diocese of Sydney until 1887 when following a recommendation from the Bishop's Plenary Council of 1885, Adelaide was made an Archdiocese by Rome. The documents arrived in Australia in 1887 and Adelaide’s fourth Bishop, Bishop Christopher Reynolds, became the first Archbishop on 10th May that same year.

The Diocese of Port Augusta became a separate diocese on the same day Adelaide became a Metropolitan Archdiocese, and the new [Port Augusta] diocese then became a province of the Archdiocese of Adelaide.

In 1951 the seat of the Port Augusta Diocese was moved from Port Augusta to Port Pirie, and became part of the Port Pirie Diocese; Port Pirie is a Suffragan Diocese of Adelaide.

The Archdiocese of Adelaide, covers an area of 105,000 sq. km in the south of the state.

Bishops and Archbishops of Adelaide   

Bishop Francis Murphy, 1844 – 1858     

Bishop Patrick Geoghegan, 1859 – 1864     

Bishop Lawrence Sheil, 1866 – 1872    

Bishop Christopher Reynolds, 1873-1887; Archbishop Christopher Reynolds, 1887 – 1893     

Archbishop John O’Reily, 1895 – 1915    

Archbishop Robert Spence, 1915 – 1934    

Archbishop Andrew Killian, 1934 – 1939       

Archbishop Matthew Beovich, 1939 – 1971    

Archbishop James Gleeson, 1971 – 1985

Bishop (Auxiliary) Philip Kennedy, 1973 – 1982 
(Auxiliary Bishop to Archbishop Gleeson)   

Archbishop Leonard Faulkner, 1985 – 2001 
    
Bishop (Auxiliary) Gregory O’Kelly, 2006 - 2009
(Auxiliary Bishop to Archbishop Wilson)

Archbishop Philip Wilson, 2001 – 2018

Apostolic Administrator Bishop Greg O'Kelly, 2018 - 2020

Archbishop Patrick O'Regan, 2020 - current