Port Gibson is a city in Claiborne County, Mississippi, United States. The population was 1,567 at the 2010 census. Port Gibson is the county seat of Claiborne County, which is bordered on the west by the Mississippi River. It is the site of the Claiborne County Courthouse.

Claiborne County is a county located in the U.S. state of Mississippi. As of the 2020 census, the population was 9,135. Its county seat is Port Gibson. The county is named after William Claiborne, the second governor of the Mississippi Territory.