The Nepton River is a tributary of Chibougamau Lake, flowing into the Municipality of Eeyou Istchee James Bay, in Jamésie, in the administrative region of Nord-du-Québec, in the province of Quebec, in Canada.

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

The Nepton River originates at the mouth of an unidentified lake (length: 1.0 kilometre (0.62 mi) altitude: 475 metres (1,558 ft)) in McCorkill Township.

From the mouth of the Nepton River, a peninsula advances in a straight line on the Southwest 1.4 kilometres (0.87 mi) in the bay to the outlet of the lake Forest.

The mouth of the Nepton River is located at 0.4 kilometres (0.25 mi) east of the boundaries of Roy and McCorkill Townships.