The Piponisiw River is a tributary of Simard Lake (Gouin Reservoir) located in the western part of the Gouin Reservoir, flowing entirely into the forest zone in the town of La Tuque, in the administrative region of Mauricie, Quebec, Canada.

The Piponisiw River valley is served by the R1045 (East-West) road that connects the R1009 (North-South) forest roads on the west side of the Gouin Reservoir and the R2046 (North-South direction) which leads south to the village of Obedjiwan, Quebec.

The surface of the Piponisiw River is usually frozen from mid-November to the end of April, however, safe ice circulation is generally from early December to late March.

The mouth of this river Head Lake is located in the Center-East part of Lacasse Township, at 0.8 kilometres (0.50 mi) west of the top of a mountain (elevation: 514 metres (1,686 ft)).

The toponym "Piponisiw River" was formalized on September 9, 1981 at the Commission de toponymie du Québec.