The decision will come as a huge disappointment to Richard Rogers, who is already working on the airport's high-profile Terminal Five building.
Fosters will team up with Arup and building services engineer Hoare Lea on the £1.5 billion scheme, which could see the demolition of the oldest parts of the airport, including Frederick Gibberd's 1950s Terminal Two and Queen's buildings ( pictured below).
'We are very excited to have assembled what we believe is the very best team to take on what is potentially for BAA an extremely important project,' said Mike Forster, business strategy director for BAA Heathrow.
'These companies were selected following a thorough assessment process and they will help us to understand the key elements of the project in the weeks and months ahead.
'It is important to stress that at this stage that these companies have been appointed for early design and development work only,' he added.
Mark Shirburne Davies, BAA Heathrow's facility solutions director, added: 'We have made these appointments swiftly as we need to commence early-stage design and development work at the end of this month.
'We received high-quality proposals from all the companies who we invited to tender.
'The selected companies are all preferred BAA suppliers: Fosters and Hoare Lea are working on multiple projects across our seven UK airports while Arup is currently working on Terminal Five,' he added.
BAA Heathrow hopes the project will start on site in 2009, and a planning application could be submitted as early as next year.