Dallas County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 6,482, making it the fourth-least populous county in Arkansas. The county seat is Fordyce. Dallas County is Arkansas's 49th county, formed on January 1, 1845; it was named for George M. Dallas, 11th Vice President of the United States.

George Mifflin Dallas was an American politician and diplomat who served as mayor of Philadelphia from 1828 to 1829, the 11th vice president of the United States from 1845 to 1849, and U.S. Minister to the United Kingdom from 1856 to 1861.