A church at Ruabon dedicated to Collen was listed in the Norwich Taxation of 1254 as Ecca Sci Colyem'.

It is not clear whether this was the present St Mary's, the dedication to Mary replacing that of Collen, or a reference to a lost chapel to the south-west of Ruabon, located at Dinhunlle Isaf.

The CPAT Churches Survey states that a church dedicated to Mary was built by the monks of Valle Crucis Abbey between 1272 and 1304, who also had possession of the church at Llangollen. The same survey also notes the tradition that the church at Ruabon was originally established by another saint, Mabon.