The Archives Office is the official archive for the Roman Catholic Archbishop of Perth, the administration of Perth Archdiocese and St Mary's Cathedral. For the most part, the parishes, agencies, schools and religious orders retain their own records. In Western Australia, the Dioceses of Geraldton (1898), Bunbury (1954) and Broome (1959) maintain a diocesan archive.  

There are collections of particular public interest which are noted in the following. The office holds sacramental records for St Mary's Cathedral and a Central Database of Baptisms. The office also holds the archives of the Congregation of the Presentation Sisters (WA) (PBVM) and the Congregation of Our Lady of the Missions (RNDM). The Catholic newspaper, The Record, is microfilmed from 1874-1980 and the microfilms are held at the State Library of Western Australia.