St Mary's Church, Kidwelly, is situated some 50m south of the Gwendraeth Fach estuary. It has been suggested that the original (pre-conquest) church was dedictaed to St Cadog. The northern churchyard boundary is curvilinear, although its south, east and west boundaries are straight, the south being bordered by Lady Street. During the medieval period the church belonged to the Deanery of Kidwelly. Between 1107 and 1115 the church was granted as a priory to the Benedictines of Sherborne Abbey by Roger, Bishop of Salisbury and lord of Kidwelly. The priory's foundation charter was issued from Roger's seat, Kidwelly Castle (NPRN 95633). The priory, whose buildings are thought to have been located to the west of the church, is thought to have always been relatively poor, with only one monk present in 1377. The priory was dissolved in 1539, at which time the patronage passed to the Crown. In 1833 the living was a discharged vicarage, still in the patronage of the Crown. In 1998 the church was a parish church in the Rural Deanery of Cidweli, and the living was a vicarage held with Llandyfaelog. A late medieval coffin lid was found on the north side of the church in 1846.

The church is a Grade I listed building, listed as the largest parish church in south-west Wales and for its exceptional broach spire and fine Decorated Gothic detail. It is constructed of mixed rubble stone with yellow oolite and Old Red Sandstone dressings, and consists of four-bayed nave, three-bayed chancel, vestry (north of chancel centre bay), three-storeyed tower with spire (north of nave west bay) and south porch. The original church reportedly burnt down in the thirteenth century. The wide nave served as the parish church during the medieval period, with the chancel being the monastic priory church. The nave was longer at this time (it is thought to have been damaged when lightning hit the spire in 1481). The chancel, nave and transepts are thought to date to the mid-fourteenth century. Decorative work includes motifs such as ballflowers, wave-mouldings and tablet-flowers (characteristic of work comissioned by Henry de Gower, Bishop of St Davids, 1328-1347). The south porch may be contemporary, although it was partly rebuilt in the post medieval period. The vestry may date to the late fourteenth century, and was originally a chancel transept, possibly the site of one of two medieval chantry chapels (that of St Michael had been founded by 1492 and St Nicholas by the later medieval period). The tower, one of the earliest in the region, dates to around 1400, and is thought to have been added against an existing nave north door. The Spire is contemporary, although it was damaged by lightning in 1481, 1681, 1854 and 1884. The tower formerly had a crenellated parapet, still present in 1833. In 1552 there were four bells, 'great and small'.The nave's west wall was rebuilt in the sixteenth century, at which time its former west bays were lost. A niche over the nave south door contained an alabaster figure of the virgin Mary after 1660, and was removed in the late 1860s (it currently lies beneath the west window). The original font was shattered by fallinf masonry in 1658. The oak belfry door is inscribed with the date 1713. The organ case dates to 1762. The porch is thought to have been rebuilt in the late eighteenth century. By 1854 the tower's parapet was no longer present.The church was restored in 1884. The oolite and portland stone font dates to this time, as are the free-standing pews. The belfry clock (replacing an earlier one) is late nineteenth century. The oolite south transept screen dates to the earlier twentieth century. The oolite reredos dates to 1932.

Sources include:
Cambria Archaeology, 2000, Carmarthenshire Churches, gazetteer, 48
Cadw, Listed Buildings Database
Richard Suggett, Painted Temples: Wallpaintings and Rood-screens in Welsh Churches, 1200–1800, (RCAHMW 2021)

RCAHMW 2021