The Keswick River is a tributary of the Saint John River in York County, New Brunswick in Canada. Early documents referred to it as Madam Keswick River.

The Keswick River watershed is entirely rural, dominated by forests and small farms in the communities of Mouth of Keswick, Burtts Corner, Zealand and Nackawic-Millville.

45°59′33.64″N 66°49′40.44″W / 45.9926778°N 66.8279000°W / 45.9926778; -66.8279000