The builder will deliver Newton Leys, Fairfield and Whitehouse Primary Schools, which will open ready for the new intake of pupils in September 2016.
Milton Keynes Council selected Willmott Dixon for its first tranche of schools through the National Major Works Framework, one of six frameworks provided by Scape Group.
The entire programme will see Milton Keynes create seven new schools as well as expand 12 schools by 2018.
Willmott Dixon is working with three architects; CORDE for Fairfield, ADP for Whitehouse and Synergy for Newton Leys.
Peter Owen, managing director at Willmott Dixon, said: “Demand for schools places across the country is outstripping supply and Milton Keynes is not unique in implementing a major school investment programme.
“The first three schools will deliver 2,000 additional primary places and by using the Scape Major Works framework, Milton Keynes will save time and cost which can instead be channelled into important areas such as front line services.
“We’ll also ensure local companies benefit as supporting the ‘local pound’ is a very important part of what we do.”
In recent years, Willmott Dixon has transformed school accommodation in Liverpool, Middlesbrough, Isle of Wight, Bedfordshire, Southampton and Warwickshire with multiple projects that replaced life-expired property or created new schools to provide extra capacity for places.