The Coaticook River is a north-flowing river rising in Vermont, United States, and located primarily in the Estrie region of Quebec, Canada. The mouth of the river is located north of Waterville and south of Lennoxville, near the southern border of the city of Sherbrooke, at the Massawippi River. Via the Massawippi and the Saint-François River, it is part of the St. Lawrence River watershed.