The stadium’s capacity is to be reduced from 80,000 to 60,000, in part to allow for the installation of boxes suitable for corporate hospitality.
Retractable seating to cover the running track and bring spectators closer to the pitch is also set to be installed on all four sides, while the roof is to be extended to provide cover to those in the front rows.
The distinctive triangular floodlights are to be reused in the newly configured stadium, which West Ham are expected to move into in summer 2016.
Before then the multi-purpose arena will host five matches of the 2015 Rugby World Cup, and is also booked for the 2017 World Athletics Championship.
The revamped stadium’s capacity for football will be 54,000, with 60,000 for other events and up to 80,000 for concerts, including standing room.