Vice-chairman Karren Brady said the deal demonstrated the club had kept its promise to regenerate two areas of east London through its stadium move and that they chose the group for its "close links to the community'.
The developer plans to build new homes on the site as well as retail and leisure facilities by 2018.
As part of any scheme talks have taken place with the family of former West Ham and England captain Bobby Moore about the possibility of placing a landscaped garden named in his honour at the centre of the site, as well as a statue of him.
In a statement, Moore's daughter Roberta Moore said: "I have always believed that there should be some form of permanent West Ham United presence at the Boleyn Ground site after the team leave and I'm really pleased that the centre point of the development is planned to be named in honour of my father."
The Hammers played their first match at Upton Park in 1904. Its official name is the Boleyn Ground, however it is commonly called Upton Park after the area it is located in and currently has a capacity of 35,000 - which will be almost double with the move to the Olympic Stadium.