St Mary's Church is located between Market Street and Longford Road in Holyhead, the principal port of the north Wales county of Anglesey.

[1] St Mary's is described in a book describing the buildings of north Wales as "a large formal square church"; the authors also noted the copper roof, and the platform upon which the church is raised.

[4] As of 2013, the parish priest is Father Frank Murray, of the Missionary Oblates of Mary Immaculate.

The parish of Holyhead also includes St Therese's Church, Rhosneigr.

£230 from collection boxes was stolen, a font was damaged, paint was poured into the speaker system, white spirit was poured across banners, and hymn books were damaged.