Johnson County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 25,749. The county seat is Clarksville. Johnson County is Arkansas's 30th county, formed on November 16, 1833, from a portion of Pope County and named for Benjamin Johnson, a Territorial Judge. It is an alcohol prohibition or dry county.

Clarksville is a city in Johnson County, Arkansas, United States. As of the 2010 census the population was 9,178, up from 7,719 in 2000. As of 2018, the estimated population was 9,743. The city is the county seat of Johnson County. It is nestled between the Arkansas River and the foothills of the Ozark Mountains, and Interstate 40 and US Highway 64 intersect within the city limits. Clarksville-Johnson County is widely known for its peaches, scenic byways and abundance of natural outdoor recreational activities.