Main contractor Sir Robert McAlpine is delivering the £350m Morello II twin tower residential development next to East Croydon station.
It has signed Mitchellson to start the groundworks on site next month.
A total of 338 flats will be built in the two towers, with a further 118 flats for shared ownership and social rent built in an adjacent 9-storey stepped complex called Cherry Orchard Gardens.
The Morello Estate project will also include 20,000 sq ft of retail and commercial floor space, new public realm and a new link bridge to East Croydon train station.
It will be funded by Mitsubishi Estate London and Menta with the Cherry Orchard Gardens estate owned and operated by Clarion Housing Association.
Independent building services contractor Briggs and Forrester is understood to have secured the MEP contract for the project.