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 town of Wrexham where the seat is located at the Cathedral Church of Our Lady of Sorrows.
The diocese was erected on February 12, 1987 from the Diocese of Menevia. The current bishop is the Right Reverend Edwin Regan, the 2nd Bishop of Wrexham.
| Tenure | Incumbent | Notes |
|---|---|---|
| February 12, 1987 to March 7, 1994 | James Hannigan | Bishop of Menevia; died in office |
| November 7, 1994 to present | Edwin Regan | Priest of Menevia; ordained December 13, 1994 |