SR 70 begins at an intersection with US 29/SR 14 (Jackson Street) in Newnan in Coweta County. The road heads northwest. Just before leaving town, it intersects SR 34 Bypass. Then, it curves to the north-northwest before curving to the north-northeast and entering Fulton County. SR 70 passes to the northwest and north of Palmetto. Just north of town, It intersects US 29 Alternate/SR 14 Alternate/SR 154. Here, SR 70/SR 154 head concurrent to the north toward Campbellton. In Campbellton, SR 92 joins the concurrency. The three routes head northwest and curve to the north-northwest and cross over the Chattahoochee River into Douglas County. Almost immediately, SR 166 joins the concurrency. The four highways head northeast and curve to the north-northeast, passing Boundary Waters Park. North of the park, SR 92 departs to the northwest, while the other three routes continue to the southeast on Campbellton Road SW. They curve to the east and cross over the Chattahoochee River for a second time, crossing back into Fulton County. Approximately 4,000 feet (1,200 m) later, SR 70 splits off to the northeast. It meets an intersection with SR 6. Just before passing by the Fulton County Airport, is an interchange with Interstate 20 (I-20) and an intersection with SR 139 (Martin Luther King, Jr. Drive SW). The highway passes along the northwestern edge of the Carroll Heights neighborhood of Atlanta. It enters the Bankhead/Bolton neighborhood area of the city just before meeting its northern terminus, an intersection with US 78/US 278/SR 8 (Donald Lee Hollowell Parkway NW).
SR 70 used to travel along Fulton Industrial Boulevard between Campbellton Road and Fairburn Road in southwestern Fulton County, However, it was re-routed over the Chattahoochee River into Douglas County, before crossing over the river again back into Fulton County. However, this stretch no longer carries a state route number.