State Route 124 (SR 124) is a state highway that runs southwest-to-northeast through portions of DeKalb, Gwinnett, Barrow, and Jackson counties in north-central Georgia. The route runs from its southwestern terminus at I-20/SR 402, US 278, and SR 12 in Lithonia to its northeastern terminus at SR 11 just southwest of Jefferson.

From here the highway splits, with the northbound lanes going to the east avoiding the county square and overlapping S.R. 20 at Buford Drive. The southbound lanes continue to overlap S.R. 20 through the county square to the intersection of S.R. 20 and Scenic Highway.