Llangyndeyrn (Welsh pronunciationⓘ) is a village, community and electoral ward in the River Gwendraeth valley, Carmarthenshire, in Dyfed region of West Wales, United Kingdom.

The Welsh language name of the village means "the church of St. Cyndeyrn".

A Welsh saint named Cyndeyrn is the equivalent of the English Kentigern and the Scottish St. Mungo; but the St Cyndeyrn associated with Llangyndeyrn is believed to be a different one, a descendant of Cunedda whose festival is on 5/6 August.

Both St Cyndeyrn's parish church and Capel Salem are grade II* listed buildings.

The community is bordered by the communities of: Llangunnor; Llanddarog; Pontyberem; Llanelli Rural; Trimsaran; Kidwelly; and Llandyfaelog, all being in Carmarthenshire and includes the villages of Pontyates, Carway and Meinciau.