Llanwnnog (also spelt Llanwnog) is a village in Powys, Wales. It is located one-and-a half miles north of Caersws in the community of the same name, on the B4568 road. The Ordnance Survey spell the name with a single 'n'. Until 1987 Llanwnog was a community.
Llanwnog's parish church is St. Gwynnog's church. The antiquarian Elias Owen was curate here from 1871 to 1875, and in 1873, the church's rood screen was restored by J W Poundley and D Walker. Llanwnnog National School, built in 1850, was designed by the architect Thomas Penson.