The A83 at the Rest and Be Thankful in Argyll has reopened under traffic-light control.
Engineers have completed a series of repairs and clear-up operations following a landslide on 13 September.
The road was inspected by Police Scotland and geotechnical specialists for a final safety check before one lane was reopened at 07:35.
Work remains ongoing, with the road safety barrier being reinstated as well as a temporary debris fence.
The nearby old military road had been used as a diversion after the main road was blocked by a "second significant landslide" in the space of six weeks.
Eddie Ross, of road operator BEAR Scotland, said: "Teams are continuing with mitigation work in the area to provide further landslip resilience to the route.
"We're also continuing with work on the next phase of catch-pit installation on the A83 which will add further landslip mitigation in the area."