Saint John River may refer to:
- Saint John River (Bay of Fundy), in Canada (mainly New Brunswick but also Quebec) and the United States (Maine)
- Saint John River (Liberia), in West Africa
See also
- St. Johns River, in Florida, United States
- St. John's River (California), in Visalia, California, United States
- St. John Rivers, a character in Jane Eyre
- Saint-Jean River (disambiguation)