The Snohomish River is a river in the U.S. state of Washington, formed by the confluence of the Skykomish and Snoqualmie rivers near Monroe. It flows northwest entering Port Gardner Bay, part of Puget Sound between Everett and Marysville. The Pilchuck River is its main tributary and joins the river at Snohomish. The river system drains the west side of the Cascade Mountains from Snoqualmie Pass to north of Stevens Pass.

Measured at Monroe, the Snohomish River has an average annual flow of 9,500 ft³/s.