Galliford Try and Vinci will stat work immediately on the redevelopment of The Grange School in Runcorn and the redevelopment of Wade Deacon High School in Widnes.
The Grange project will combine a nursery, infant, junior and high schools as one institution.
New plans for Wade Deacon High School are to build a 500 seat auditorium, 6 court sports hall and specialist teaching facilities, all within the one school building.
The contractors will keep the historic frontage of the Lower Wing building but everything behind will be brand new.
Both schools survived the Government BSF review, which saw the Halton Schools BSF reduced from a £167m building programme.