Browne Willis, Rice Rees and A.W. Wade-Evans agree on the dedication of the church to Cynog, although there is no known evidence for the dedication prior to the eighteenth century.

Theophilus Jones gave the dedication as Mary in 1809, although in his view the original dedication has been to Gwnlen or Gunleus, a tradition that persisted in the nineteenth century, as the church is dedicated to Gundleus on the recorded on first edition OS map, and Gynlais on the second edition OS map. Jones made the connection of the name Gunleus with the Welsh Gwynllyw, but this does not appear to have any early precedent. The place-name derives from the river name Cynlais, attested in the twelfth century.