Cilmery, sometimes spelt Cilmeri, is a village in the county of Powys, mid Wales. Lying 2 miles west of Builth Wells and south of Newbridge on Wye, the village is bound by two rivers, Afon Chwefri and the Afon Irfon. The Afon Irfon is famed for the Prince of Wales, Llywelyn Ein Llyw Olaf, being killed on its banks in December 1288.

The village possesses a memorial stone at Cefn –y- Bedd in memory of Llewelyn ap Griffith's final battleground. Llywelyn led the Welsh resistance to the inevitable invasion by Edward I. By the end of 1282 Llywelyn was dead, having been killed on 11th of December in a brief engagement with English forces at Irfon Bridge near Cilmery.

2.5 miles to the east of Cilmery is the popular town of Builth Wells (Welsh: Llanfair ym Muallt). Builth is famed for its many attractions including the annual Royal Welsh show. There are several walks and pleasant drives and it is a popular tourist destination. Moelfre mountain is situated under 2 miles to the south and has a popular downhill mountain bike trail as well as walking trails.

Cilmeri straddles the A483 which runs from Swansea to Chester. The train station at Cilmeri runs from Shrewsbury to Swansea on the Heart of Wales line and has 4 trains passing through it per day in each direction.