Llangenny is a village in the Brecon Beacons National Park, Powys, Wales. It is in the lower reaches of the Grwyne Fawr. The Vale of Grwyney community consists of Glangrwyney, Llanbedr, and Llangenny.
Three features in Llangenny are the grade II* listed St.Cenau or Saint Keyne parish church, the Dragons Head Inn and Cwm Barn, an old barn converted into accommodation. The population is approximately 100.
The area is popular with hill-walkers and for camping and outdoor activities.