Balfour Beatty was appointed as preferred bidder for the project in January 2015 and since then, alongside the University, has worked to secure detailed planning consent for the development.
Balfour will invest almost £23m taking at 80% stake in the scheme, which it will design, build, and operate for 50 years.
The £200m financing of the project represents the largest UK wrapped inflation linked bond, post the financial crisis.
The first phase of additional accommodation is expected to be ready for the start of the 2018/19 academic year.
Balfour Beatty now boasts a student accommodation portfolio of nearly 5,000 beds in development or operation in the UK.
University of Sussex finance director, Allan Spencer said: “The bond allows the East Slope Residences project to proceed and facilitates a key element of the University’s strategy to accommodate more students on our campus and to provide high quality residences with more social space and amenities.”
The University has invested over £200m in the last few years to redevelop its campus, with both landmark academic and residential facilities.
Balfour Beatty Investments Director, Ian Woosey, said: “We believe the fact that a bond of this size was able to achieve such attractive pricing demonstrates the underlying strength of the sector.”