Benton County is a county in the U.S. state of Iowa. As of the 2020 census, the population was 25,575. Its county seat and largest city is Vinton. The county is named for Thomas Hart Benton, a U.S. Senator from Missouri.

Thomas Hart Benton, nicknamed "Old Bullion", was an American politician, attorney, soldier, and longtime United States Senator from Missouri. A member of the Democratic Party, he was an architect and champion of westward expansion by the United States, a cause that became known as Manifest Destiny. Benton served in the Senate from 1821 to 1851, becoming the first member of that body to serve five terms.