State Route 109 (SR 109) is a state highway that runs west-to-east through portions of Troup, Meriwether, Pike, and Lamar counties in western Georgia. The route runs from its western terminus at Alabama AL CR 278 and the Alabama state line, west of LaGrange, to its eastern terminus at SR 18 between Barnesville and Zebulon.

The route is a main thoroughfare for West Point Lake campgrounds at its western terminus. When it changes to Chambers County Road 278 in Alabama, the road still continues to serve West Point Lake campgrounds. SR 109 then crosses over West Point Lake on its way east, and meets up with US 29/SR 14 to go through downtown LaGrange. During this section, SR 109 serves West Georgia Medical Center. Also during this section, LaGrange College is placed as well as the home of the Callaways, owners of Callaway Gardens. On the east side of the square, US 29/SR 14 splits off to the north while crossing US 27/SR 1/SR 219. From there it runs past LaGrange Mall to serve I-85/SR 403 at Exit 18. Subsequently, SR 109 is mostly a two lane road with an occasional passing lane with the surroundings usually being farmland or forest, and runs to the town of Greenville. Here SR 109 meets with SR 18 and is co-signed with SR 18 until Molena.

Right after Greenville, SR 109 Spur angles off to the northeast to continue to Gay. SR 18/SR 109's next junction is just outside of Woodbury at SR 85 Alt Then in Woodbury, SR 74 joins SR 18/SR 109 after crossing SR 85. SR 18/SR 74/SR 109 continue to just south of Molena, where SR 74 bears south to continue to Thomaston. Just north of Molena, SR 18 continues north to cross U.S. 19/SR 3, while SR 109 turn east to also cross and briefly overlap with US 19/SR 3, before reaching its eastern terminus at SR 18.

State Route 109 Spur connects SR 18 and SR 109 near Greenville to SR 74/SR 85 in Gay. This road was designated because of the long distance on SR 74/SR 85 connecting Gay and SR 109 in Woodbury. This also helps smooth traffic going to the Cotton Pickin' Fair in Gay.