St Mary's Church was built in 1882-1883 to replace the old St Mary's Church (NPRN 103828) at Llanfair ar y Bryn, on the outskirts of Llandovery (some 5.5km to the south-west). Although the old St Mary's Church was parish church to Llanfair-ar -y-Bryn parish, it is situated some 1.5 km south of the parish boundary, in the parish of Llandingat. The new St Mary's Church is located within the parish and is now the parish church. When it was erected, the old St Mary's Church became a chapel of ease to Llandingat parish. The church is situated within a rectilinear churchyard, adjacent to the former vicarage (NPRN 17614) (depicted as 'Beeches' on modern Ordnance Survey mapping). According to tradition, a Cistercian grange was sited here. Two twelfth century carvings, depicting Adam and Eve in expicit tradition of the Sheila-na-gig, are thought to have been found here. They are now in Carmarthenshire County Museum, Carmarthen.

The buidling, to the designs of Archibald Ritchie, is constructed of rock-faced stone, and consists of nave and chancel, large south porch and north vestry. The former west bellcote has been removed. The building has a bare interior with arch-braced nave roof and a chancel arch on square capitals with stylised leaf carving. The east window has stained glass of 1933, by C.C. Powell.

Sources include:
Lloyd, T, Orbach, J and Scourfield, R, 2006, The Buildings of Wales: Carmarthenshire and Ceredigion

N Vousden, RCAHMW, 20 March 2013