Columbia County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 22,801. The county seat is Magnolia. The county was formed on December 17, 1852, and was named for Christopher Columbus. The Magnolia, AR Micropolitan Statistical Area includes all of Columbia County.

Magnolia is a city in Columbia County, Arkansas, United States. As of the 2010 census the population was 11,577. The city is the county seat of Columbia County.