[6] Brantley County is part of the Brunswick, Georgia metropolitan statistical area.

[7] Although the precise origin of the county name is unknown, it is believed that it honors U.S. Representative (congressman) William Gordon Brantley or his father, Benjamin Daniel Brantley, a well-known local merchant and Confederate States Army soldier in the American Civil War (1861-1865).

The county's eastern border area, east of Waynesville, is located in the Cumberland-St. Simons sub-basin of the St. Marys-Satilla River basin.

[14] As of the 2020 United States census, there were 18,021 people, 6,823 households, and 4,578 families residing in the county.

The last Democrat to carry the county was Bill Clinton in 1992, and it has swung hard to the right in the following elections.