It is probable that the battlemented and diagonaly butressed tower was built in or just after 1401 when an earlier church on this site was torched by the Welsh during the revolt led by Owain Glyndwr. The arrowslits and corner plinths plus a stair turret are all signs that, like many other churches in the area, it was built as much for security and lookout purposes as religeous ones. A beacon lit above the turret would be clearly visible from nearby New Radnor castle.

The rest of the church was rebuilt within the next 50 years in what is known as the perpendicular style and its size and proportions along with many embellished details are evidence that it may have been rather more than a parish church, perhaps with collegiate or conventual status. The large font dates from far earlier than the church and may well be as early as the 8th century. Legend associates it with the group of four ancient standing stones to the south of Kinnerton. The interior of the church is dominated by two fine pieces of woodcraft.

The main screen of 1470 - 1500 is one of the finest in Wales and is of a type associated with a Gloucestershire school of carvers. It was originally painted and guilded, adding to its beauty and grace but this was removed in a restoration of 1858. The outstanding carved and panelled organ case is 16th century and is the oldest surviving example in the British Isles. The organ itself was put into the case in 1872 and some changes were made to the layout of the panels at that time, yet the rich carving and ornamental dragons and beasts are of exceptional quality and like the screen would have been painted and guilded originaly.

It is improbable that this was the work of local craftsmen and it is possible that it came from Worcester Cathedral as the Dean and Chapter of that establishment were patrons of this church after the Mortimers and the Crown.