State Route 100 (SR 100) is a state highway that runs south-to-north through portions of Meriwether, Troup, Heard, Carroll, Haralson, Polk, Floyd, and Chattooga counties in western Georgia. The route runs from its southern terminus at US 27, SR 18, SR 41, and SR 109 in Greenville to its northern terminus at US 27, SR 1, and SR 114 in Summerville.

The route begins at the intersection of U.S. Route 27 and Georgia State Routes 18, 41 and 109 in Greenville in Meriwether County in west-central Georgia. Moving north, SR 100 joins SR 54 just east of the interchange with Interstate 85 east of Hogansville. Once in Hogansville, SR 100 turns north co-signed with U.S. Route 29/Georgia State Route 14 for a short distance before continuing northwest alone. Southeast of Franklin, Georgia, SR 100 joins U.S. Route 27/Georgia State Route 1. Just west of Franklin, SR 100, along with SR 34, splits from U.S. 27 and continue west. In less than a mile, SR 100 splits from SR 34 and continues northwest. SR 100 continues north and becomes co-signed with SR 5 for a short time east of the Georgia/Alabama state line before continuing north. As SR 100 moves toward Tallapoosa, it crosses Interstate 20 where it is the first eastbound exit in Georgia. Crossing U.S. Route 78 in Tallapoosa, SR 100 becomes co-signed with U.S. Route 27 south of Cedartown, Georgia. South of Cedartown, SR 100 turns west following U.S. Route 278 for a brief time before resuming a northwestern path. In Cave Spring, Georgia, SR 100 turns west for a brief distance co-signed with U.S. Route 411 before turning north once again. SR 100 turns west co-signed with Georgia State Route 20 for a short distance before resuming its northern course toward Summerville. SR 100 ends at the intersection of also U.S. Route 27 and Georgia State Route 114 in Summerville in Chattooga County in northwest Georgia.