Ronneby is an unincorporated community and census-designated place in Maywood Township, Benton County, Minnesota, United States. As o…Ronneby is an unincorporated community and census-designated place in Maywood Township, Benton County, Minnesota, United States. As of the 2010 census, its population was 67. The community is located along State Highway 23 near Benton County Road 6.