The castle’s history stretches back centuries, with the O’Kennedy family as its earliest known owners. By 1640, John Kennedy held the property, but the political upheavals of the late 17th century would dramatically alter its ownership. During the Commonwealth period of 1654-6, the castle was recorded as being partially repaired at public expense and featuring a small barbican. Colonel Henry Prittie received a land grant from Charles II in 1678 that included Dunalley Castle, though his fortunes took a turn when James II’s Dublin parliament attainted him in 1689.

The castle witnessed considerable drama during the Williamite Wars, when disbanded soldiers loyal to James II besieged it for 21 days. According to historical accounts, they eventually gained entry through treachery and threw Henry Prittie from the castle’s summit, though remarkably he survived the fall unharmed. The Prittie family’s connection to Dunalley would prove enduring; in 1800, Henry Prittie became the 1st Lord Dunalley, taking his title from this very castle. By 1840, the Ordnance Survey documented the castle as largely ruined, with only fragments of walls remaining up to 16 feet high at the northwest corner. The surveyors noted the building’s internal dimensions as approximately 20.5 feet east to west and 19.75 feet north to south, with limestone walls about 6.5 feet thick, mixed with grit-stones and grouted together.

The castle’s final chapter came in the late 1970s when commercial quarrying operations completely destroyed what remained of the medieval structure. The site that once hosted sieges, noble families, and centuries of Irish history now lies beneath a large pond created by the quarrying work. Local tradition also speaks of an abbey founded here around 540 CE, though no traces remain, and the area once contained an old church with an attached burial ground that served as the Prittie family’s place of sepulture.