St. Joseph is an unincorporated community and census-designated place (CDP)[3] in Riverdale Township, Kossuth County, Iowa, United States.

Iowa Highway 408 leads east from St. Joseph 7 miles (11 km) to Lu Verne.

According to the U.S. Census Bureau, the St. Joseph CDP has an area of 0.85 square miles (2.2 km2), all land.

One of the earliest histories states "the town was never laid out, as far as the records show, but grew by evolution."

St. Joe began its official existence in 1865 when Oscar Hale, the first landowner of the area, started a post office and hotel.

[6] Since the town of St. Joe is small and unincorporated, the community's life and activities revolve almost entirely around their church and school.