It is entered through a round-headed doorway in the church wall itself, as if the two structures share a kind of architectural intimacy, and tradition has long held that it served as the priest's house, possibly incorporating the church sacristy as well.

The building is compact, measuring just under six metres north to south and a little over five metres east to west, yet it carried genuine domestic and liturgical complexity. Five corbels survive in both the east and west walls, the stone projections that once supported the timber joists of an upper floor, and fireplaces were recorded within. On the ground floor, the east wall contains an ogee-headed window, the ogee being a graceful S-curved arch associated with late medieval craftsmanship, fitted with three leaden bar-holes, a hanging-eye, spudstone, and a draw-bar socket, suggesting a room that could be secured and was considered worth securing. Beside it sits an aumbry, a small recessed wall cupboard typically used to store sacred vessels or other valuables. The OS six-inch maps of both 1842 and 1920 show the building abutting the church in its present position, though a slight gap now developing between its west wall and the church's north wall hints at the slow, incremental movement of old masonry. The antiquarian Thomas Johnson Westropp noted the priest's house identification in the early 1900s, giving the tradition at least a century of documented recognition.

Standing flush against the doorway that connects the two structures is a large table tomb, a flat-topped raised monument measuring nearly three metres in length, with a plaque set into the wall above it. The inscription reads: "1706. I.H.S. This tumbe is made by Fa. Con Mullan, for him and his family in his ancestors Chapel. To whom God be merciful." The phrase "his ancestors Chapel" is the detail worth pausing on. Father Con Mullan was not simply commissioning a tomb in a convenient church; he was burying himself, as he saw it, in a family place, in a building his own people had some prior claim to. That sense of layered ownership, of a priest's house becoming a family chapel across generations, gives the small structure beside Kilkeedy Church a significance that its modest footprint does not immediately suggest.