State Route 126 (SR-126) is an 11-mile-long (18 km) route in Montgomery County. The route serves as both the northern and southern frontage roads between exits 11 and 16 along Interstate 85 (I-85) and U.S. Route 80 (US-80). Prior to US-80's realignment onto I-85 in November 2010, SR-126 was only the northern frontage road. SR-126 begins at itself, a consequence of the realignment as it forms a complete loop. A 308-foot-long (94 m) spur from the route's beginning marks end of the route.

State Route 126 is a two-lane route that runs parallel to Interstate 85 and U.S. Highway 80. State Route 126 is routed directly north of the southbound lanes of I-85, and US-80 is routed directly south of the northbound lanes. Both State Route 126 and US-80 are in clear view of the Interstate Highway route between Mileposts 12 and 21 along I-85. State Route 126 crosses over and has an interchange junction I-85 at Waugh, and reaches its eastern terminus less than one mile (1.6 km) southeast of I-85 at its second junction with US-80.

The entire route is in Montgomery County.