SR 124 begins in Weakley County in Greenfield at an intersection with US 45E/SR 43/SR 54.

The highway then passes through the community of Pillowville, where it has an intersection with SR 190.

SR 124 continues east through rural areas to enter McKenzie just shortly before crossing into Carroll County.

The highway then merges onto Cedar Street and continues southeast through downtown before coming to an intersection with US 79/SR 76.

The entire route of SR 124 is a two-lane highway.