The proposed scheme will create a new pavilion as well as conference and exhibition facilities to allow the open-air site to be used all year round.
Working under the name David Grindley Robert de Grey Architects, the architects are the first to get their hands on the National Bowl since it opened in the 1970s.
The project will increase the capacity of the arena, which was constructed from the spoil removed during the building of Milton Keynes, from 65,000 up to a massive 75,000.
Included in the redevelopment proposals are plans to build a skateboarding park which, it is hoped, will become a 2012 Olympic venue if the sport becomes classified as an Olympic event.
Timescales for the scheme, which is being backed by developers Gaming International and ClearChannel Entertainment, are not yet known, although the first phases of the work could start by the end of the year.