McDuffie County is a county located in the U.S. state of Georgia. As of the 2020 census, the population was 21,632. The county seat is Thomson. The county was created on October 18, 1870 and named after the South Carolina governor and senator George McDuffie.

Thomson is a city in McDuffie County, Georgia, United States. The population was 6,814 at the 2020 census. The city is the county seat of McDuffie County. Thomson's nickname is "The Camellia City of the South", in honor of the thousands of camellia plants throughout the city. Thomson was founded in 1837 as a depot on the Georgia Railroad. It was renamed in 1853 for railroad official John Edgar Thomson and incorporated February 15, 1854 as a town and in 1870 as a city. It is part of the Augusta – Richmond County Metropolitan Statistical Area.