Kier was an early favourite to take the job having secured the adjacent business school contract for the university.
The seven-storey building will be built on the site of Fairview House, at the corner of Park Street and Vicarage Street, and will include the latest technology, study spaces and of course, books.
Chris Tredget, Managing Director at Willmott Dixon, said: “As a local company, with an office in nearby Hitchin, and staff living across Bedfordshire, we are naturally very proud to be responsible for an important addition to our community.
“We will also buy local construction materials whenever possible to support jobs and companies in the local area.”
The latest development forms part of the University’s plans to invest some £90m at Luton campus over the next five years and follows new campus developments at Luton over recent years.
These include the new £34m Campus Centre, a £20m Postgraduate and Continuing Professional Development Centre and the Fitzroy Court Student Village, on Vicarage Street, next to the Luton campus.
Willmott Dixon’s Northern Homes Counties team will start building works this month, with the library’s completion expected in summer 2015.