Llanarthney (Welsh: Llanarthne) is a village and community in Carmarthenshire, Wales, located 7.5 miles to the east of Carmarthen and 6 miles to the south-west of Llandeilo. It has a population of 738, of whom 61% are Welsh-speaking (2001 UK Census). At the 2011 Census the population had reduced slightly to 765.
The community is bordered by the communities of: Llanegwad; Llangathen; Llanfihangel Aberbythych; Gorslas; Llanddarog; Llangunnor; and Abergwili, all being in Carmarthenshire.
It has been home to the National Botanic Garden of Wales since 2000.
Coordinates: 51°52′N 4°08′W / 51.867°N 4.133°W