Wates will start work in April 2012 on the James Hornsby High School, Basildon, De La Salle School, Basildon and Shorefields School, Clacton.
Work is due to be completed in 2013.
Ian Vickers, Regional Director for Wates said: “As Education specialists, we will bring our expertise to the projects ensuring flexible teaching and learning environments.
“Not only will we be building buildings, but we also want to make a lasting difference in the community.
“We have committed to ensuring 70% of our labour comes from the local area providing many employment opportunities.
“Additionally, as part of our proposals we have also committed to working with each of the schools to provide a number of apprenticeships, work experience placements and technology days – enriching the student’s education experience.”
Councillor Derrick Louis, Essex County Council Cabinet Member for Central Services said: “Wates have a very successful track record of delivering large scale building projects and their proposal demonstrated they can meet the very high standards we expect from our preferred bidder.”