Early European traders in the Carolinas settled along the Pee Dee River from the 17th century, including in an isolated area called Sandy Bluff.

They did business with numerous tribes, including the Choctaw and Chickasaw to the South.

However, four years later it was renamed as Marion County, in honor of Brigadier General Francis Marion,[3] the famous "Swamp Fox" and a hero of the American Revolutionary War.

[4] As of the 2020 census, there were 29,183 people, 11,600 households, and 7,532 families residing in the county.

At the 2010 census, there were 33,062 people, 13,058 households, and 8,881 families living in the county.

[15] At the 2000 census,[16] there were 35,466 people, 13,301 households, and 9,510 families living in the county.

25.40% of all households were made up of individuals, and 9.70% had someone living alone who was 65 years of age or older.

Religious Census, residents of Marion County are predominately Protestant.

[20] As of April 2024, some of the largest employers in the county include Coca-Cola Consolidated, the city of Mullins, Domtar, Goodyear Tire and Rubber Company, and Walmart.