What remains today is primarily the northwestern angle tower and a section of the north wall, both constructed from limestone. The tower, which rises four storeys high, features the remnants of a barrel vault over the first floor and two garderobes built into the north wall at first-floor level. The surviving windows display a mix of architectural styles, including a simple slit window, an ogee-headed window, and a flat-headed window, though curiously, no evidence of a doorway has been found.

Archaeological surveys reveal the tower house originally measured approximately 9.1 metres along its southern side and 12 metres along the western wall, with walls nearly a metre thick. The structure was built atop an earthen mound, which is still visible today, particularly in the southeastern and southwestern quadrants where it rises about 1.8 metres above the surrounding ground level. A defensive fosse, or ditch, about three metres wide once encircled the base of this mound, with a causeway providing access from the south-southwest.

The site holds additional archaeological interest beyond the tower house itself. Immediately north lies what appears to be a moated site, whilst a circular enclosure can be found to the south; however, neither of these features are visible above ground today. These elements suggest Knigh Castle was part of a larger defensive complex, typical of Anglo-Norman settlements in medieval Ireland, where multiple layers of fortification provided security for the inhabitants during uncertain times.