Madison County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 16,521. The county seat is Huntsville. The county was formed on September 30, 1836, and named for Madison County, Alabama, the home of some early settlers. They also named the county seat after Madison County in Alabama's county seat, Huntsville.

Huntsville is a city in and the county seat of Madison County, Arkansas, United States. The population was 2,879 at the 2020 census, up from 2,346 in 2010. During the American Civil War in 1862, it was the site of what became known as the Huntsville Massacre. Huntsville is part of the Northwest Arkansas region.