When Pope Pius IX judged that the time was right to re-establish the Catholic hierarchy in Wales and England in 1850, the southern half of the Welsh District became the Diocese of Newport and Menevia.

Boundaries were redrawn to cover Glamorgan, Monmouthshire and Herefordshire and renamed the Diocese of Newport in 1895.

In 1916, with no change to boundaries, the bishop was raised to the archbishop status with the see title becoming the Archdiocese of Cardiff.

[3] As all of the Roman Catholic dioceses in Wales are part of the ecclesiastical province of Cardiff-Menevia the history of the archdiocese and its suffragan dioceses are intertwined: The current ecclesiastical territory of the archdiocese comprises the Welsh principal areas of Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Carmarthenshire, Ceredigion, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Newport, Pembrokeshire, Rhondda Cynon Taf, Swansea, Torfaen, the Vale of Glamorgan and the part of Powys comprising the historic counties of Brecknockshire and Radnorshire, with the English county of Herefordshire.

[needs update] There are a total of eleven deaneries in the archdiocese, each of which cover several churches in that area, overseen by a dean.