FCC Environment, formerly called the Waste Recycling Group, will build the £100m Greatmoor energy from waste plant, which has already gained planning permission, as part of the deal.
Up to 300 construction jobs will be sustained through the three-year construction phase.
FCC is using Hitachi Zosen Inova as its main process engineering contractor.
Dan Murphy, project director for FCC Environment, said: “We are delighted we have been awarded the contract to construct and operate the Greatmoor energy from waste facility and are able to provide an integrated waste management solution for Buckinghamshire.
“We are now looking forward to concluding final contract negotiations with the council.
The EfW plant will burn up to 300,000 tonnes of waste each year and generate 22MW of electricity – almost enough for all of the homes in the South Bucks District.