The project is the first of three proposed schemes that Wates will deliver across the North West, with a £7m project at Hartford High School in Northwich and a £3.8m project for Upton Heath Primary to follow in June next year.
The buildings have been designed by Sheppard Robson.
Construction will start on the Maghull High School project in January with the scheme replacing facilities that are no longer fit for use. Once completed in Spring 2019, the existing building will be demolished.
The work forms part of the ESFA’s Priority School Building Programme 2 to rebuild or refurbish those school buildings in the very worst condition across the country.
The previous frameworks saw Wates collaborate on 56 schools across the country.
Tony Shenton, Business Unit Director, Wates Construction North West, said: “We are privileged to be continuing our role in the enhancement of the North West’s education infrastructure and the critical part it plays in the development of the region’s young people.”