Carter County is a county in the U.S. state of Oklahoma. As of the 2020 census, the population was 48,003. Its county seat is Ardmore. The county was named for Captain Ben W. Carter, a Cherokee who lived among the Chickasaw.

Ardmore is the county seat of Carter County, Oklahoma, United States. The population was 24,725 at the time of the 2020 census, a 1.8% increase over the 2010 census figure of 24,283. The Ardmore micropolitan statistical area had an estimated population of 48,491 in 2013. Ardmore is 90 miles (140 km) from both Oklahoma City and Dallas/Fort Worth, Texas, at the junction of Interstate 35 and U.S. Highway 70, and is generally considered the hub of the 13-county region of South Central Oklahoma, also known by state tourism pamphlets as "Chickasaw Country" and previously "Lake and Trail Country". It is also a part of the Texoma region. Ardmore is situated about 9 miles (14 km) south of the Arbuckle Mountains and is located at the eastern margin of the Healdton Basin, one of the most oil-rich regions of the United States.