It stands in a roughly circular llan (Welsh for an enclosed piece of land, particularly around a church) north of the road between Trefdraeth and Bethel.

[7] No part of any 7th century building survives, and restoration over the years has removed much historical evidence for the church's development.

Henry Rowlands, Bishop of Bangor 1598–1616, was rector of Trefdraeth during his episcopacy, as the income from the parish was attached to the bishopric.

[5] Near the eastern end of the church is a transept or chapel on the south side of the chancel, from which it is separated by a step down and an arch.

The transept has a 19th-century two-light arched window in its south wall, which contains the oldest stained glass in the church: 15th-century fragments of a crucifixion scene.

[3] The church is entered through the porch to the west end of the south wall of the nave, which leads to an arched doorway.

There are two 18th-century slate plaques on the walls by the south door commemorating those who made donations to the poor of the parish; one has names from 1761, the other from 1766.

On the opposite wall, a 17th-century slate plaque commemorates Hugh ap Richard Lewis and his wife Jane (died 1660 and 1661 respectively).

The internal timbers of the roof, some of which are old, are exposed, but there is a decorated panelled barrel-vaulted ceiling above the sanctuary at the east end of the church.

Externally, an 18th-century brass sundial on a slate pedestal was noted, as was a weathered decorated stone on the lychgate, thought to be from the 10th century.

Cadw (the Welsh Assembly Government body responsible for the built heritage of Wales and the inclusion of Welsh buildings on the statutory lists) also notes that the church's "simple design [remained] unaltered during the extensive programme of church re-building and restoration on Anglesey in the 19th century.

"[3] In 1833 Angharad Llwyd described the church as "a small neat edifice", with "an east window of modern date and of good design".

[7] Similarly, the 19th-century publisher Samuel Lewis said the church was a "small plain edifice" that could hold nearly 300 people.

[19] In 1846 the clergyman and antiquarian Harry Longueville Jones wrote that the church "has been lately repaired in a judicious manner, but without any restoration of importance being attempted, and is in good condition".

He also noted the new slate roof, the "mostly open and plain" seats, and the "very large cemetery ... commanding an extensive view".

[21] A 2006 guide to the churches of Anglesey describes St Beuno's as being in "a pleasant and quiet rural location".