Forms of the Welsh place-name incorporating Cybi are attested from the thirteenth century, although they do not certainly attest the dedication of the church to Cybi, but of the town and Cybi's 'fort'. The Life of Cybi links him with Anglesey, and given the absence of any other dedications to him on Anglesey, this adds weight to the presumption that Cybi was the principal patron of the church of the town that bears his name.

A capel-y-bedd in the churchyard may have originally housed the shrine of Cybi and relics.