The rectangular bawn, measuring roughly 31 by 26 metres, was built from uncoursed rubble stone without the typical defensive base-batter found in many similar structures. Originally, it would have enclosed and protected the main castle or tower house, with at least two flanking towers providing defensive positions; today, only fragments of this once-imposing defensive wall remain standing.

The best-preserved section is along the southern wall, where about half the original structure still rises to just over three metres in height. Here, keen-eyed visitors can spot the splay of what was once a window or defensive gun loop, though ivy now obscures much of the external stonework. The southwestern corner retains its circular angle tower, a compact defensive position just 1.8 metres across internally, pierced with four gun loops that would have allowed defenders to cover the approaches to the bawn. These narrow openings, each about 40 centimetres wide, are classic features of 17th-century Irish defensive architecture.

Much of the bawn has been lost to later development; a 19th-century house and farm buildings were constructed along where the western wall once stood, whilst modern concrete has replaced most of the northern wall. A farm gate along the southern wall may mark the original entrance, and an old roadway shown on 1836 Ordnance Survey maps still leads to the site, possibly following the route that visitors and residents would have taken four centuries ago. Despite these alterations, the remaining stonework at Rosduff provides tangible evidence of how landowners once fortified their holdings during one of the most contested periods in Irish history.