What survives is a low rubble bank, nowhere taller than about ninety centimetres and two to three metres wide, tracing the outline of a rectangular structure roughly twenty-nine metres from east to west and ten and a half metres from north to south. It sits within a small rectangular enclosure, and immediately to the south-east lies a holy well, that most persistent of Irish sacred features, where the combination of water, a defined precinct, and a place of worship signals a site that was almost certainly in use long before any surviving stonework was laid.

The pairing of church and holy well within a single enclosure is a pattern repeated across early Christian Ireland. Such enclosures, often roughly rectangular and defined by a bank or ditch, typically marked the boundary of a sacred site, separating the ritual space from the surrounding land. The wells associated with them were frequently dedicated to local saints, their waters credited with curative or protective qualities, and they continued to draw visitors for centuries after the churches themselves fell out of use or collapsed entirely. At Killabeg, the church structure is described as poorly preserved, meaning the rubble bank is essentially all that remains to indicate the building's plan. The enclosure dimensions, seventy-five metres east to west and thirty metres north to south, suggest a site of modest but deliberate scale, not a major ecclesiastical centre but a local place of worship embedded in its community and its particular piece of ground.