The monument is oval in plan, measuring roughly 24 metres on its longer axis, and what survives of its defining earthwork is a scarp, essentially a raised bank formed from the original upcast soil, rather than the more dramatic ramparts found at better-known sites. The interior is so thoroughly riddled with badger setts that the ground has become noticeably uneven, giving the enclosed area an almost churned quality that speaks more to centuries of animal occupation than to any human disturbance.

A ringfort, or rath, was typically the enclosed farmstead of an early medieval family, dating broadly to the period between the fifth and twelfth centuries. This one at Ballynahow uses the River Ara itself as a natural boundary along its western to north-eastern arc, supplemented on the remaining sides by the earthen scarp and a fosse, the shallow ditch dug to provide material for the bank. The fosse here runs roughly north-north-east to west-south-west, with an overall width of just over nine metres, though it is shallow at around 0.2 metres depth and has been slightly cut into at the north-west where a watering point was made in the river bank at some later date. The scarp is most intact along its western to northern stretch, where it reaches a width of 5.5 metres and a height of two metres, while the south-west to north-west and north-east sections have been worn down by the same badger activity that has unsettled the interior. A possible entrance, roughly two metres wide, is visible at the south-east.

The monument has been fenced off from the rest of the field, though the fence itself cuts through the fosse at the eastern and southern sides, an arrangement that protects the interior while inadvertently adding a further layer of modern intrusion to a site already shaped by generations of incremental change.