The highway connects Willacoochee and Talbotton, via Ocilla, Fitzgerald, Cordele, Vienna and Oglethorpe.

The portion of the highway in Junction City, that is concurrent with SR 96, is part of the Fall Line Freeway, a divided highway that spans the state from Columbus to Augusta, and is also signed as SR 540.

SR 90 begins at an intersection with US 82/SR 520 (Main Street) in Willacoochee, within Atkinson County.

It heads north-northeast on North Vickers Street and curves to the northwest.

The three routes head concurrent to the north, past Cumbee Park to an intersection with US 319/SR 32/SR 35 (4th Street).

In the southern part of Fitzgerald, they meet SR 107 (Benjamin H. Hill Drive), which acts as a partial bypass of the city.

The highway heads to the north-northwest and meets the southern terminus of SR 215, which takes on the "Dewey McGlamry Road" name, while SR 90 heads west on Salem Church Road.

The route intersects the southern terminus of SR 233 (Sundew Road) and curves to the southwest and crosses into Turner County before entering Rebecca.

On the southeastern edge of Cordele, it intersects the eastern terminus of SR 33 Connector (Rockhouse Road East).

The two routes run concurrent through town, until SR 230 departs to the south on Davis Avenue.

In Junction City, it meets SR 96/SR 540 (Fall Line Freeway), and they travel concurrently to a point just west of town.

Then, they pass the Oak Hill Cemetery, before they meet an intersection with US 80/SR 22/SR 41 (Washington Avenue).