Known as North 23rd Avenue, the state highway runs 2.5 miles (4.0 km) from U.S. Route 441 (US 441) east to SR 24 within Gainesville.

SR 120 heads east as a four-lane undivided highway through a mixed residential and commercial area.

6th Street) and enters the northeast quadrant of Gainesville at an abandoned rail line.

East of the address axis, SR 120 intersects County Road 329 (Main Street) and continues through a residential area.

The roadway continues east across the Waldo Road Greenway, which parallels the eastbound side of SR 24, to a gate for the Tacachale developmental disability community.