Inchiquin Castle is called after the original O'Quin stronghold of Inchiquin, O'Quin's Island on Lake Inchiquin. It may have been built by Teige-an-Chomhaid O'Brien who died in 1466. It belonged to Turlough, son of Murrogh, first baron of Inchiquin, in 1542.

Murrogh O'Brien, the fourth baron, was in possession in 1580. Situated on the northern side of the lake, it was the residence of the O'Brien family whose descendant, the Marquess of Thomond, derived his title of Earl of Inchiquin from this estate.

During O'Donnell's raid on Clare it was attacked and captured by Maguire of Fermanagh, one of his lieutenants. Some time after this a more comfortable house, sometimes referred to locally as the banquet hall, was added to the old castle.

Part of the old castle tower can still be seen and a good portion of the banquet hall is still intact. Christopher O'Brien, Murrogh the Burner's brother, lived here during the Confederate Wars. Murrogh's son, Colonel John O'Brien, abandoned Inchiquin towards the end of the seventeenth century. By then it was in a ruinous condition.