Knighton is a market town and community on the River Teme, straddling the border between Powys, Wales and Shropshire, England. It lies in the traditional county of Radnorshire. Originally an Anglo-Saxon settlement, Knighton is located on Offa's Dyke, the ancient earthwork that divided the two countries. It later became a Norman defensive border town.

The River Teme rises in Mid Wales, south of Newtown, and flows southeast roughly forming the border between England and Wales for several miles through Knighton before entering England in the vicinity of Bucknell and continuing east to Ludlow in Shropshire. From there, it flows to the north of Tenbury Wells on the Shropshire/Worcestershire border on its way to join the River Severn south of Worcester. The whole of the River Teme was designated as an SSSI by English Nature in 1996.