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

Adelaide 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 it became a Suffragan of the Archdiocese of Adelaide.

In 1951 the seat of the Diocese of Port Augusta was moved from Port Augusta to Port Pirie and was renamed the Diocese of Port Pirie.

The Diocese of Darwin (est. 1938) is also a Suffragan Diocese of Adelaide.

The Archdiocese of Adelaide covers an area of 105,000 sq. km in the south of the state of South Australia and comprises over 50 parishes.

Bishops and Archbishops of Adelaide and their Tenure Dates