The Conestogo River is a river in Waterloo Region and Wellington County in Southwestern Ontario, Canada. It is in the Lake Erie Basin and joins the Grand River as a right tributary at the community of Conestogo.
A dam built on the river for flood control formed Conestogo Lake, which covers an area of about 23 square kilometres. A conservation area operated by the Grand River Conservation Authority is located on this lake.
Fish species in the river inclued brown trout, pike, smallmouth bass, perch, walleye and carp.