The Mildred River is a tributary of La Trêve Lake, flowing in regional County Municipality (RCM) of Eeyou Istchee James Bay (municipality), in the administrative region of Nord-du-Québec, Canadian province of Quebec, in Canada.

The lower section of the Mildred River flows successively through the townships of Turgis, Julien, Lantagnac and Guettard.

The hydrographic slope of the Mildred River is accessible on road 113 linking Lebel-sur-Quévillon to Chibougamau.

The surface of the Mildred River is usually frozen from early November to mid-May, however, safe ice movement is generally from mid-November to mid-April.

The mouth of the Mildred River located at: The toponym "Mildred River" was formalized on December 5, 1968, at the Commission de toponymie du Québec, i.e. at the creation of this commission [3] Download coordinates as: