The county is named for Jett Thomas, an officer in the War of 1812 who is also known for overseeing the construction of the first building at the University of Georgia (originally referred to as Franklin College and known today as Old College) as well as the state capital at Milledgeville.

[4] The northwestern half of Thomas County, bordered by U.S. Route 319 southwest of Thomasville, and a line that ends up bisecting the distance between Coolidge and Pavo in the northeast, is located in the Upper Ochlockonee River sub-basin of the larger Ochlockonee River basin.

The southeastern portion of Thomas County, running southeast from Thomasville, is located in the Aucilla River sub-basin of the larger Aucilla-Waccasassa basin.

As of the 2020 United States census, there were 45,798 people, 17,595 households, and 12,161 families residing in the county.

Colleges and universities: There are two school districts:[17] Private schools: Similar to other Georgia counties on the Florida border, the county is reliably Republican in presidential elections, having last voted for a Democrat in 1980 when the Democrat was native Georgian Jimmy Carter.