The building stretches 19.5 metres north to south and encompasses two storeys above a vaulted basement, its octagonal pillars possibly dating to the 14th century. The first floor houses a grand hall that runs parallel to the street; this space was recorded as 'Ketleryshall' as early as 1432, hinting at the building's long association with the infamous Alice Kyteler, the wealthy moneylender accused of witchcraft in 1324.

The inn's architecture tells the story of centuries of urban life in medieval Ireland. A round-headed doorway with hood-moulding, visible at the northern end of the front wall, reveals that the original street level sat considerably lower than today's pavement. The building follows a classic medieval urban plan, with the main house connected by a link building to a square courtyard at the rear, much like the nearby Rothe House. The north gable preserves several architectural gems: single and two-light chamfered windows, some adorned with hood-mouldings, whilst a round-headed two-light window graces the wall extending eastward from the gable.

Archaeological investigations by Margaret Gowen in the mid-1990s uncovered fascinating evidence beneath the inn's foundations. The excavations revealed deeply stratified, waterlogged deposits that speak to the ambitious reclamation of the River Nore's floodplain during the 13th and 14th centuries. The site's yard contains two domestic wells, discovered during the 1966 restoration work, including St. Kieran's Well, which yielded a 13th-century font now housed in St. Francis' Abbey. These layers of history, from medieval merchant commerce to accusations of sorcery, make Kyteler's Inn not just a pub but a tangible link to Kilkenny's rich and sometimes dark past.