Janesville is a city in Waseca County, Minnesota, United States. The population was 2,256 at the 2010 census.U.S. Highway 14 serves as a main route in the community, running east–west, south of Janesville. County Road 3 runs north–south through the town. There is one disabled stoplight, now a four way stop, in Janesville at the intersection of County Road 3 and old Highway 14.