The Cornwallis River is in Kings County, Nova Scotia, Canada. It has a meander length of approximately 48 kilometres (30 mi) through eastern Kings County, from its source on the North Mountain at Grafton to its mouth near Wolfville on the Minas Basin. The lower portion of the river beginning at Kentville is tidal and there are extensive tidal marshes in the lower reaches. In its upper watershed at Berwick, the river draws on the Caribou Bog while a longer branch continues to the official source, a stream on the North Mountain at Grafton.

Kings County is a county in the Canadian province of Nova Scotia. With a population of 62,914 in the 2021 Census, Kings County is the third most populous county in the province. It is located in central Nova Scotia on the shore of the Bay of Fundy, with its northeastern part forming the western shore of the Minas Basin.