Work will now begin this summer on a 400m 2venue for temporary exhibitions and a 200m 2gallery earmarked for Eastbourne's nationally acclaimed Towner art collections.
The new Towner collection facility will allow many more paintings to be exhibited, although work not displayed will be stored in a purpose-built unit.
The building, to be sited adjacent to the Grade II-listed Congress Centre in Devonshire Park, will also boast an art research studio dedicated to photography and conservation work.
Other features include a shop, café, conference and exhibition spaces and a suite of community activity rooms for schools and local groups.
Commenting on the project, a practice spokeswoman said: 'The new building will bring a 21st-century addition to Devonshire Park and strengthen its position as the town's cultural quarter.'
by Clive Walker