According to the historian Carrigan, writing in 1905, Kilree derives from Cill Ruidhche, the church of St Ruidhche, a female saint commemorated on the 8th of February. That the site is now conventionally associated with Bridget says something about how local dedications can shift over centuries. The church itself sits within a remarkable grouping: a round tower rises just seven metres to the north-west, and a high cross stands roughly fifty-five metres to the west, making this one of the more complete early ecclesiastical ensembles in the county.

The church's fabric holds a compressed account of early Irish building practice. The original structure, now the nave, dates to the 10th or 11th century and is built of limestone rubble in rough courses, with antae, projecting extensions of the side walls beyond the gables, that are characteristic of early Irish church architecture. Entry was through a trabeate doorway in the west gable, meaning the lintel was flat rather than arched. When John O'Donovan visited in 1839 for the Ordnance Survey, that original doorway was already blocked, and he noted a replacement opening inserted at the west end of the south wall, itself subsequently blocked again. The three levels of putlog holes still visible in the side walls are evidence of the cantilevered timber scaffolding used during construction, a detail that brings the original building campaign unexpectedly close. A chancel was added to the east, probably in the 12th century, its side walls keyed into the existing antae. The original round-headed chancel arch, built of cut stone jambs and voussoirs springing from a plain impost, was later compromised when a cruder pointed arch was inserted within it, the two archways now occupying the same space and marking two distinct moments of use. The chancel retains a piscina, a small wall basin used for rinsing liturgical vessels, at its eastern end, as well as an altar tomb and two graveslabs. One sandstone window head in the south chancel wall appears to have been reused from an earlier structure, sitting visibly awkwardly on its limestone jambs. Repairs carried out in 1945 and 1946 reduced the height of the west gable and added two buttresses to arrest its outward lean, interventions that are now themselves part of the building's long record of piecemeal alteration.