Choctaw County is a county located in the central part of the U.S. state of Mississippi. As of the 2020 census, the population was 8,246. Its northern border is the Big Black River, which flows southwest into the Mississippi River south of Vicksburg. The county seat is Ackerman.

Big Black River is a river in the U.S. state of Mississippi and a tributary of the Mississippi River. Its origin is in Webster County near the town of Eupora in the north central part of the state. From there it flows 330 miles (530 km) in a generally southwest direction until it merges with the Mississippi River 25 miles (40 km) south of the city of Vicksburg. It is the major contributor to the Big Black River Basin. It forms part of the northern border of Choctaw County, passes through Montgomery County, and forms the eastern border of Holmes County and the northern border of Claiborne County.