Llanarmon Dyffryn Ceiriog is a village in Wrexham County Borough, Wales. It lies on the River Ceiriog and is at the end of the B4500 road, five miles (8 km) south-west of Glyn Ceiriog and ten miles (16 km) north-west of Oswestry. It is within the Ceiriog Valley ward, Clwyd South Senedd constituency and Clwyd South UK parliamentary constituency. It is in the community of Ceiriog Ucha ("Upper Ceiriog").