The site first appears in historical records in 1289 as “Cathyrgilmorr” and was held by T. f. Maurice in 1298. During the Tudor period, the castle changed hands several times; in 1564, one Dom. White of Limerick acquired it after redeeming it from the late Earl of Desmond and purchasing it from its rightful owner. By 1583, it was recorded as the castle and village of “Cahir a Gillimo” in the Desmond Rebellion records.

The Stritch family maintained control of the castle for several generations during the 17th century. James Stritch held it in 1639, following in his grandfather’s footsteps, and by 1655, W. and E. Stritch were recorded as the castle’s owners. After the Cromwellian settlement, the property was granted to Captain Robert Morgan and A. Reymon in 1667. The Down Survey map of 1654-7 depicts Caherguillamore as a tower house structure in Glenogra Parish, giving us a valuable visual record of its appearance during this turbulent period.

Today, little remains of the original castle. According to antiquarian Thomas Johnson Westropp’s early 20th-century survey, only a rectangular foundation survives, located about 45 metres east of a stone ring fort. Local tradition holds that stones from the castle ruins were used to build a structure in 1835, suggesting the castle had already fallen into considerable decay by the early 19th century. Despite its ruined state, Caherguillamore Castle represents centuries of Irish history, from medieval stronghold to contested Tudor property, through to its eventual abandonment and repurposing by local communities.