St Edern's also owns three pieces of 19th-century church silverware, but a silver chalice dated 1574 was lost some time during the 19th century.

He appears as "Edern ap Nudd", one of the knights of King Arthur, in the Mabinogion (a collection of medieval Welsh prose tales).

The oldest part is the nave, which has been described as "essentially 14th-century", although it was rebuilt in 1871 during restoration work under Henry Kennedy, architect of the Diocese of Bangor.

[15] In 1849, the writer Samuel Lewis noted that the college and Queen Anne's Bounty (a fund to support poor clergy) had recently each paid £400 for a new parsonage.

[15] St Edern's is built in the Perpendicular style using local stone, with blocks of cut sandstone as the external face.

[3] The church's entrance is an arched outer doorway in the porch, with a 15th-century pointed inner door set in a square frame described by one architectural guide as "boldly moulded".

[3][6][10] The second of the three steps leading up from the chancel to the sanctuary at the east end is decorated with encaustic tiles, with the Welsh words Golchaf fy nwylaw mewn diniweidrwydd ath allor o Arglwydd a amglych hynaf ("Wash my passion away with innocence at the altar of the Lord here").

[3] The east and south chancel stained glass is in memory of the wife, son, and daughter of Hugh Wynne Jones, who died in the mid-19th century.

[3][6] There is a softwood panel screen between the nave and chancel, decorated with carved flowers and fruit, with a frieze of acanthus leaf.

The reredos (the screen behind the altar) has further carved panelling, as does the upper section of the rectangular pulpit, a reading desk, the communion rail and a table.

The college's archivist has described the chancel as containing "a startling assemblage" of panels, "patched together in jigsaw fashion" and "heavily varnished".

The author noted that church records from 1776 to 1831 included mention of another silver chalice, dated 1574, with other references to a flagon and a paten made from pewter, but these were no longer to be found.

[3] Cadw (the Welsh Government body responsible for the built heritage of Wales and the inclusion of Welsh buildings on the statutory lists) also notes "some finely detailed fittings including the chancel screen, reredos, pulpit and reading desk with 17th-century carved panels, and also a late 18th-century gallery at the west end.

In 1833, the Anglesey antiquarian Angharad Llwyd described the church as "a small ancient structure, displaying some good architectural details".

[19] In 1862, the clergyman and antiquarian Harry Longueville Jones wrote that the church was "of good work, and with the details of doors and windows carefully elaborated.