The county was created on December 3, 1832, and was named for George Rockingham Gilmer, a politician who served two nonconsecutive terms as governor of the state.

[3][4] Gilmer County is home of the annual Apple Festival, which is held in mid-October.

Poultry raising and processing make up the largest portion of the agricultural economy, which generates 33.2% of the total revenues.

In 1832, Gilmer County was organized as Georgia started to encroach on Cherokee territory.

It also has a growing tourist sector, some based on whitewater kayaking and canoeing on the rivers in the area.

Farming is still important, although, by 2002, the area of land in the county devoted to agriculture had declined to 24,700 acres.

Agriculture and directly related businesses, such as landscape services, generate $565.1 million, or 33.2% of the county's economic output.

[11] As of the 2020 United States Census, 31,353 people, 12,021 households, and 8,028 families were residing in the county.

As of the 2010 United States census, 28,292 people, 11,314 households, and 8,000 families lived in the county.

Other current government officials include: Sheriff, Stacy Nicholson; Probate Judge, Scott Chastain; Magistrate Judge, Kevin Johnson; Clerk of Court, Amy Johnson; Tax Commissioner, Rebecca Marshall; Coroner, Jerry Hensley.

Some of the past chairmen of the board of commissioners include J.C. Sanford (2011-2014), Mark Chastain (2009–2010), Jerry Farist (2005–2008), and Rayburn Smith (1997–2004).

Merle Howell served as the first chairman of the three-member board starting on January 1, 1996.

She was recalled by the voters of Gilmer County, who elected Rayburn Smith in July 1997.

The first five-member board included Mack Logan, Ruel Reece, Garvin Davis Jr., John Penland, and Charles Aaron.

The voters of Gilmer, like neighboring Rabun, Towns, Pickens, and Fannin Counties, were different in their historic partisan preferences from other parts of Georgia.

In contrast, these northern Georgia counties voted for Republican presidential candidates in several early 20th-century elections.

James Dickey's novel Deliverance was set on a fictional river modeled on the Coosawattee, prior to the construction of the dam producing Carters Lake.