State Route 99 (SR 99) is a state highway that runs south-to-north through portions of Glynn and McIntosh counties in southeastern Georgia. The route runs from its southern terminus at US 82 and SR 520 east of Waynesville to its northern terminus at I-95/SR 405 west of Eulonia.

The southern terminus of SR 99 is at its junction with U.S. Route 82 / State Route 520 in southern Glynn County. The road follows a northerly route to its junction with State Route 32 just west of Sterling. SR 99 overlaps SR 32 for approximately 2 miles (3.2 km) to the junction with U.S. Route 341/U.S. Route 25/State Route 27 where SR 32 ends. SR 99 continues north through rural Glynn County to its junction with Interstate 95 at exit 42 and on to U.S. Route 17/State Route 25 in northern Glynn County. From there, SR 99 continues co-signed with US 17/SR 25 to Darien in McIntosh County where SR 99 branches off to the east and forms a loop from Darien to Eulonia through several neighborhoods, while closely following the gradient between the trees and marshes. In Eulonia, SR 99 once again intersects US 17/SR 25, where it continues west one more mile to its terminus at an interchange with Interstate 95 at exit 58. Continuing westward, the roadway becomes State Route 57, which continues west towards Townsend.