Thomasville is the county seat of Thomas County, Georgia, United States. The population was 18,881 in 2020. The city deems itself the "City of …Thomasville is the county seat of Thomas County, Georgia, United States. The population was 18,881 in 2020. The city deems itself the "City of Roses" and holds an annual Rose Festival. The city features plantations open to the public, a historic downtown, a large farmer's market, and an oak tree from about 1680 at the corner of Monroe and Crawford streets.