The diocese covers Anglesey, most of Caernarfonshire and Merionethshire and the western part of Montgomeryshire.

[1] As with the rest of Wales, it initially resisted the papal mission of St Augustine of Canterbury in Britain.

[citation needed] The Report of the Commissioners appointed by his Majesty to inquire into the Ecclesiastical Revenues of England and Wales (1835) found the see had an annual net income of £4,464.

[citation needed] After a brief restoration with the Holy See during the reign of Queen Mary I, the diocese remained part of the Anglican Province of Canterbury until the early 20th century.

[9] It is named after St Beuno, to whom a church in the area is dedicated, and the medieval commote of Uwch Gwyrfai.

[11] This was formed in 2016[15] by the union of the parishes of Caerhun-with-Llangelynnin, Conwy, Gyffin and Upper Llanbedr.

[32] This was formed by the union of the parishes of Betws-y-Coed, Dolgarrog, Dolwyddelan, Llanrhychwyn, Penmachno and Trefriw.

[46] 1original dedication to St Anne 2may be still open This was formed by the union of the parishes of Bettws Garmon, Caernarfon, Llanbeblig, Llanfair-is-Gaer Griffith's Crossing and Llanfair-is-Gaer St Mary.

[49] It is named after St Peblig, to whom is dedicated the original parish church of Caernarfon.

[56] It is named after St Tudno, to whom is dedicated the original parish church of Llandudno.

[62] 1original dedication to St Bodfan This was formed by the union of the parishes of Carno, Llandinam, Llangurig, Llanidloes, Llanwnnog, Penstrowed and Trefeglwys.

[69] This was formed by the union of the parishes of Cemais, Corris, Darowen, Esgairgeiliog, Llanbrynmair, Llanwrin, Machynlleth, Mallwyd and Penegoes.

[72] As of September 2024 it was served by one Ministry Area Leader, one Associate Priest and one Distinctive Deacon.

[73] 1original dedication to SS Ust & Dyfrig This was formed by the union of the parishes of Bryncoedifor, Dolgellau, Llanelltud and Llanfachreth.

[80] This was formed by the union of the parishes of Abererch, Beddgelert, Criccieth, Denio, Dolbenmaen, Llanarmon, Llangybi, Llanystymdwy, Porthmadog St John, Porthmadog St Cyngar and Treflys.

[89] This was formed by the union of the parishes of Aberdaron, Llanbedrog, Llanengan, Llanfaelrhys, Llangian, Llannor and Pwllheli.

[92] This was formed by the union of the parishes of Botwnnog, Bryncroes, Edern, Llandudwen, Llangwnnadl, Llaniestyn, Nefyn, Penllech, Pistyll and Tudweiliog.

[111] This was formed by the union of the parishes of Aberdyfi, Abergynolwyn, Arthog, Fairbourne, Llanegryn, Llanfihangel-Y-Pennant, Llangelynnin, Llwyngwril, Tal-Y-Llyn and Tywyn.

[114] 1original dedication to St Egryn This was formed by the union of the parishes of Aberffraw, Gaerwen, Llanffinan, Llanfihangel Ysgeifiog, Llangadwaladr, Llangaffo, Llangristiolus, Trefdraeth Christ the King and Trefdraeth St Beuno.

[119] This was formed by the union of the parishes of Bodedern, Bryngwran, Caergeiliog, Llanbabo, Llanfachraeth, Llanfaelog, Llanfair-Yn-Neubwll, Llanfihangel-Yn-Nhywyn, Llangwyfan, Llantrisant, Llanynghenedl, Llechylched and Valley.

[120] It is named after Saint Kevin of Glendalough, to whom a redundant church in the area is dedicated.

[133] This was formed by the union of the parishes of Llanedwen, Llanfairpwllgwyngyll, Llanfair-yn-y-Cwmwd, Llangeinwen, Llanidan and Newborough.

[137] This was formed by the union of the parishes of Amlwch, Llanallgo, Llandyfrydog, Llaneilian, Llaneugrad, Llanfihangel Tre'r Beirdd, Llanwenllwyfo and Penrhosllugwy.

[140] This was formed by the union of the parishes of Bodewryd, Cemaes, Llanbadrig, Llanfaethlu, Llanfair-Yng-Nghornwy, Llanfechell, Llanfflewin, Llanrhuddlad, Llanrhwydrus and Rhosbeirio.

[150] This was formed by the union of the parishes of Llanbedrgoch, Llandegfan, Llandysilio, Llanfair Mathafarn Eithaf, Llansadwrn, Menai Bridge and Pentraeth.

[151] It is named after Saint Tysilio, to whom the ancient church of Menai Bridge is dedicated.