Ringway Infrastructure Services is main contractor on the £14.7m scheme to improve the A57 from the Todwick crossroads to Junction 31 of the M1 motorway.
Coun. Gerald Smith, Cabinet Member for Regeneration and Development for Rotherham Borough Council, said: "It has been a long and very frustrating process over the years but we will finally see the work start on this much-needed scheme in September.
"This road carries high levels of traffic so it needs to be as safe as possible but it has been troubled by road safety and congestion problems for years. It is also vital for the continued regeneration within the Dinnington area."