On 27 June 2012, Pope Benedict XVI appointed the then Monsignor Brignall, who was at that time the Diocese of Wrexham's Vicar General, to succeed the retiring bishop, Edwin Regan.

The diocese covers an area of 8,361 km² of the ancient counties of Anglesey, Caernarfonshire, Denbighshire, Flintshire, Merionethshire and Montgomeryshire (the local government areas of Conwy, Anglesey, Denbighshire and Flintshire, Gwynedd, Wrexham and the former Montgomeryshire).

The see is in the city of Wrexham where the seat is located at the Cathedral Church of Our Lady of Sorrows.

Where known, the date of installation and ordination as bishop are listed in the notes together with the post held prior to appointment.)

There are a total of six deaneries in the Diocese of Wrexham, all of which cover several churches in that area, overseen by a dean.