A £154million contract to transform the Olympic Stadium has been awarded to engineering firm Balfour Beatty.
Works aimed at ensuring a sporting, cultural and commercial legacy include the construction of a warm-up athletics track, hospitality facilities and external landscaping.
The stadium will host five matches at the Rugby World Cup 2015, as well as become the permanent home of West Ham United FC and the national stadium for athletics.
A community athletics track, for use by the local community, will also be built.
Work will begin early this year and is set for completion by Spring 2016.