AR 123 begins in Clarksville and runs east, crossing AR 103. The route concurs with US 64 for a stretch until Lamar. North of Lamar the route meets AR 164 and AR 292 before winding to enter Ozark National Forest. Once in the forest, the route winds until meeting AR 7 and AR 16. The route leaves this concurrency at the Lurton Loop, after which the route heads north to exit the forest. The route meets AR 74 for a short distance before continuing to Western Grove, where the route terminates at US 65.