Gloucestershire County Council has awarded the firm a three-year extension to look after the area's roads. Atkins will oversee transport planning and traffic management along with highway maintenance and design until 2014.
"This is a testament to the team's hard work and success and we will continue to drive improvement," said division managing director Philip Hoare.
Gloucestershire's cabinet lead for environment Stan Waddington said: "We still have areas that we need to improve, such as the state of our unclassified roads and the huge potholes problem, but we are getting there."
The firm has also been appointed lead consultant to the Windsor and Eton relief road and Eton-Slough spur road. It will provide design and works supervision for the road, which includes lining it with mature trees.
Royal Borough of Windsor and Maidenhead lead member for highways and street care Colin Rayner stressed: "The relief road is in desperate need of repairs to ensure that it remains safe and meets today's more stringent safety standards."
The £7 million project will be funded by the South East England Partnership Board and DfT regional transport fund following a successful bid by the council.
The project is scheduled to be completed by December 2011. The road is a key transport link to Dorney Rowing Lake, site of the London 2012 Olympic rowing events.