Norton Rose has finalised a deal which will see the firm move into new Foster and Partners-designed headquarters in 2007.
The building is to be built by developers More London, and Norton Rose have agreed bespoke elements including layout with Foster and Partners. It will be situated near City Hall on the south bank of the Thames, and totals 340,000 sq ft.
Foster and Partners are responsible for several landmark buildings including 30 St Mary Axe, better known as the Gherkin.
Norton Rose chief executive Peter Martyr said the building would be an excellent working environment for staff as well as an architectural statement.