An exhibition of the £6.7 million designs were opened at the station last Thursday by the Scottish Transport Minister, Nicol Stephen, who described them as 'the first step towards a bigger, better rail network for all of Scotland'.
The client is Network Rail on behalf of the Scottish Executive and the design team includes Arup and Turner & Townsend.
The project focuses on access-friendly vertical circulation - lifts and escalators transport passengers between the station and a 'new front door' on Princes Street.
Jefferson Sheard's Tom Rhys Jones said he was 'delighted that the practice's new Edinburgh office has secured such a prestigious commission'.
The project will start on site in January 2006.