The Archbishop of Westminster heads the Roman Catholic Diocese of Westminster, in England. The incumbent is the metropolitan of the Province of Westminster, chief metropolitan of England and Wales and, as a matter of custom, is elected president of the Catholic Bishops' Conference of England and Wales, and therefore de facto spokesman of the Catholic Church in England and Wales. All previous archbishops of Westminster have become cardinals. Although all the bishops of the restored diocesan episcopacy took new titles, like that of Westminster, they saw themselves in continuity with the pre-Reformation Church and post-Reformation vicars apostolic and titular bishops. Westminster, in particular, saw itself as the continuity of Canterbury, hence the similarity of the coats of arms of the two sees, with Westminster believing it has more right to it since it features the pallium, a distinctly Catholic symbol of communion with the Holy See.

The Diocese of Westminster is a Latin archdiocese of the Catholic Church in England. The diocese consists of most of London north of the River Thames and west of the River Lea, the borough of Spelthorne, and the county of Hertfordshire, which lies immediately to London's north.