Jamie Fobert Architects has been selected for the next stage of the development of Tate St Ives in Cornwall.
The practice - which last year won a competition to refurbish and extend the Kettle's Yard Gallery in Cambridge - saw off the gallery's original designer, Evans & Shalev, which was also on the shortlist.
The other firms that made it into the competition's last round were Caruso St John Architects, Cottrell & Vermeulen Architecture, Marks Barfield Architects and Stanton Williams.
The victorious practice will now further develop designs for a building on the Barnoon Car Park, which sits above the existing gallery.
The new space will provide an education centre for the first time and will allow the gallery to organise exhibitions all year round without having to close between installations.
The project is being delivered through a partnership between Cornwall County Council, Penwith District Council and the Tate itself.by Ed Dorrell