The new station will be mainly manufactured off-site at O’Rourke’s factory near Sheffield.
Work is due for completion in December 2015 and will include a new ticket hall, an interchange with the Docklands Light Railway and step-free access between the platforms and street level.
The station will have a roof made from the transparent plastic material, EFTE, similar to the material that was used at the Eden Project in Cornwall.
Hoardings will go up around the site next week ahead of demolition of the old North London Line station, which closed in 2006.
Roger Robinson, Laing O’Rourke’s CEO Europe, said: “We’re immensely proud to commence delivery of the latest station for London’s most important strategic rail project, and we look forward to applying our innovative engineering techniques to support its construction.”