The London Legacy Development Corporation will move into Westfield's One Stratford Place office development from May 2012.
The location next to the Olympic Park will help the Development Corporation to oversee the £292 million (approx. 350 million) transformation of the Park after the Games into a new part of London, along with attracting private investment from across the world.
The Olympic Park Legacy Company is being reformed into the London Legacy Development Corporation on April 1, 2012 to continue to develop, manage and maintain the future Queen Elizabeth Olympic Park over the next 20 years.
The new body will also take on new powers and responsibilities for the Park and surrounding areas including planning powers and the building of physical and economic connections from the Park to existing communities.
The Development Corporation will occupy the 10th floor of the building which will also be used by the British Olympic Association and British Paralympic Association for Team GB House during the 2012 Games.
Andrew Altman, Chief Executive of the Olympic Park Legacy Company, said: "With the switch to the London Legacy Development Corporation, we will be moving closer to the Olympic Park so that we are ready to take operational control as soon as the 2012 Games finish.
"We will be in the right location to showcase the Queen Elizabeth Olympic Park to private investors along with overseeing the creation of a new piece of London that will offer thousands of new homes, jobs and business opportunities."
John Burton, Director of Westfield Stratford City, said: "Having secured two major occupiers in quick succession, we are confident of Stratford's status as an emerging business location. We now have some exciting prospects in play for the remaining space and strong interest in the pre-let opportunities."
The Olympic Park Legacy Company is currently based at East Thames House in West Ham Lane, Stratford.
CBRE and Cushman & Wakefield are the office leasing agents appointed by Westfield.
Source: MJ2 Limited