The Holmeside Triangle development would provide a department store, shops, cafes, restaurants and apartments in the south of the city centre, attracting £135 million of investment and creating up to 1,200 jobs.
Newcastle-based architecture firm Red Box is working with Sunderland Arc to produce a masterplan for the site as part of a planning application that is due to be submitted to Sunderland City Council next year.
The Farringdon Row project will transform a 3.5ha derelict cliff-edge site overlooking the River Wear into a mixed-use development of around 400 apartments, 7,000 sq m of office space and 1,000 sq m of leisure facilities.
Sunderland Arc expects to have a £70 million masterplan prepared by February 2004, with work on site beginning in 2005.
Sunderland Arc deputy chief executive Jonathan Bretherton said the projects illustrate "the great strength of having an urban regeneration company in a city".