Dillon County is a county located in the U.S. state of South Carolina. As of the 2020 census, the county's population was 28,292. The county seat is Dillon.

Dillon is a city in Dillon County in eastern South Carolina, United States. It is the county seat and largest city of Dillon County. It was established on December 22, 1888. Both the name of the city and county comes from James W. Dillon, an early settler and key figure in bringing a railroad through the area. The population was 6,788 in the 2010 U.S. census.