Llandegley is situated close to the A44 road, between Rhayader and Kington, in Powys, Mid Wales. Llandegley sits to the north east of Llandegley Rocks, close to Mithil Brook that feeds the River Ithon some 2 miles, 3km, to the west of the village.

Llandegley derives it name from the church of St Tecla, who gave the village its former name Llandegla. The saint was famous in olden times for her kindness to sufferers from the 'falling sickness', a form of epilepsy. Sufferers would visit Llandegley in the hope of a cure. Firstly they'd wash in one of the many wells in the area, then make an offering to a woman giving a hen, a man giving a cockerel, and to the saint, before spending the night under the communion table.

The age of St Tecla's church is unknown but it is believed that it dates back to the medieval age. It was rebuilt in 1874 and at one point contained a musicians' gallery. Today a medieval screen still remains, as well as an impressive priest's door, which is believed to have come from nearby Cwmhir abbey. The church tower was rebuilt in 1953 after the previous one was destroyed by a gale in March 1947.