Approximately 700t of structural steelwork will be erected by A C Bacon Engineering for the project that incorporates both secondary and primary schools.
It will also feature enhanced community sports facilities, funded by Chelmsford City Council.
The project consists of four steel-framed buildings: a single storey nursery building, a single and part two-storey primary school building, a three-storey U-shaped secondary school and a large sports hall.
Councillor Tony Ball, Essex County Council’s Deputy Cabinet Member for Education, said: “It’s a wonderful facility, but not just the school but the community facilities as well.
“It has been excellent working with the Chelmsford Learning Partnership and we’re very much looking forward to the first ‘through school’ in Essex. It’s something I’m very pleased to see.”
The school will eventually accommodate 1,200 secondary students and 420 primary pupils in two adjoining premises. The primary school is expected to open in September 2018, with the secondary school opening a year later.