Llangynyw (also Llangyniew) is a hamlet and community in Montgomeryshire, Powys, mid Wales.

It is located on a hill inside a bend in the River Banwy, approximately two miles north-east of Llanfair Caereinion.

The community includes the hamlet of Pontrobert.

The focus of the hamlet is the Parish Church of St. Cynyw, which dates from between 1450 and 1500 and is a Grade II* listed building.

Pentre Camp, an Iron Age hillfort, is near the hamlet.