Canon Island Abbey is a ruined Augustinian monastery located on the extreme northeast corner of Canon Island on the River Shannon in County Clare, Ireland. The abbey was founded in 1189 under the sponsorship of Donal Mór Ua Briain (Donald O'Brien), the king of Thomond. The ruins include a rectangular church measuring 26 meters long and 7 meters wide. Two chapels are accessible via the north wall. The kitchen and refectory are situated to the south of the cloister.