What remains is a subrectangular outline, roughly 14.2 metres east to west and 5.8 metres north to south, defined by a collapsed stone wall that now stands no higher than 1.2 metres at its best. The quoins, the dressed corner stones that would once have given the building its structural definition, have been removed entirely, probably taken long ago for use elsewhere. Inside the footprint, possible grave markers survive beneath the vegetation, suggesting this was not merely a place of worship but also of burial.

The church takes its name from the townland of Killosheheen, and the "kill" prefix, derived from the Irish "cill", indicates an early ecclesiastical enclosure or church site, a naming pattern common across the west of Ireland and often pointing to origins in the early medieval period. The building's modest dimensions and simple subrectangular plan are consistent with small rural churches found throughout Connacht, many of which served local communities for centuries before falling out of use and into disrepair. By the time the site was surveyed and catalogued in D. Lavelle's 1994 archaeological survey of the Ballinrobe district and the areas around Lough Mask and Lough Carra, the structure was already heavily overgrown and poorly preserved, its stones reclaimed in part by the landscape around it.