The ground beneath it is thought to be the site of an ancient parish church, one of those cases where a later structure was raised directly on the footprint of its predecessor, erasing the earlier building in the process while inheriting its sacred ground.

The church visible today was built in 1812, as recorded by Brady in 1863. That date places it in a period of considerable Church of Ireland building activity across Ireland, when many rural parishes were either constructing new churches or substantially rebuilding older ones. Whether the 1812 structure was a straightforward replacement of a medieval or early modern parish church, or whether it incorporated any earlier fabric, is not recorded. What is noted is that the ancient parish church of Killeagh almost certainly stood on this same spot, and the nineteenth-century building probably occupies that original site. The qualifier matters: the physical evidence of the earlier church has not survived in any documented form above ground, and what remains is largely a matter of reasonable inference from the pattern of the graveyard and the continuity of parish identity.