A sheela-na-gig is a carved stone figure, typically female and explicitly sexual in pose, found on churches and castles across Ireland and Britain; their precise purpose remains debated, though theories range from apotropaic warnings against lust to pre-Christian fertility symbols absorbed into ecclesiastical architecture. One of the two here is set into the exterior east gable wall; the other is built into a quoin, the cornerstone, at the northeast angle of the chancel. Their presence on a church that was otherwise constructed with considerable care and refinement gives the site an quietly unsettling double character.

The building itself is substantial and detailed. The nave measures nearly seventeen metres in length internally, built from coursed limestone masonry and finished with stepped battlements along the side walls, giving it a martial silhouette more common to tower houses than parish churches. The west gable carries a 15th-century triple-light window with ogee heads, a curving S-shaped arch form fashionable in late medieval Irish ecclesiastical work, and above it rises a triple bellcote with steps still leading up to it. Entry to the nave is through opposed north and south doorways with pointed arches and chamfered jambs; the apex of the south doorway exterior features a carved mitred head and a zoomorphic figure on the moulding stop. Inside, a red sandstone stoup, a small basin for holy water, is fixed to the south wall, and the chancel, reached through a segmental chancel arch, contains corbels projecting from the east wall at altar level. The sacristy, attached at the southeast corner, has a vaulted ground floor with wall presses, an external stair to a first floor room, and a fireplace, suggesting a space that doubled as a working domestic chamber for the officiating clergy. The most affecting interior feature is the altar tomb of Maud Plunkett, who died in 1494, bearing a recumbent effigy of a woman in a horned cap, a fashionable headdress of the period.

The church lies within the demesne of Malahide Castle, accessible to visitors who come to the castle and its surrounding parkland north of Dublin. Until 2010, heavy tree and vegetation growth obscured much of the southern facade, and its removal revealed the full extent of the south elevation for the first time in living memory. The east gable, where one of the sheela-na-gigs is positioned, repays close attention, as does the detailing around the south doorway. The sacristy exterior stair and the bellcote steps are among the more unusual surviving features of the structure, giving a sense of how fully articulated this building once was.