UTC Swindon will specialise in engineering, business, enterprise and entrepreneurship for 14 to 19-year-olds.
Building work is due to begin in the autumn after detailed designs have been finalised.
The grade II listed old school building and the water tower will be key parts of the site. BAM plans to restore the water tower to its former glory and renovate all the existing buildings as well as fitting a new canopy over the courtyard.
The proposed Mill site off Bristol Street is still subject to lease negotiations, planning permission and Government approval.
Paul Inman, Pro Vice-Chancellor at Oxford Brookes University, which is a UTC sponsor, said: “BAM’s design work for the buildings are both refreshingly innovative and complementary to the engineering heritage.”
Simon Peet, Engineering Manager at Johnson Matthey Fuel Cells, said: “The next project priority is to finalise the design with BAM Construction and in parallel progress with the Planning and English Heritage approval, before the capital funding approval in the summer.”