Gareth Hoskins Architects will carry out the four-year project to revamp the Scottish National Gallery in Edinburgh, a project that will overhaul the building designed by William Playfair.
The revamp will see the display of Scottish art - currently in the gallery's basement - "radically overhauled and significantly expanded".
The gallery attracts more than one million visitors a year but Sir John Leighton, director general of National Galleries Scotland (NGS), has said the display of Scottish art there was one of the institution's "enduring weaknesses".
Building work will not start until 2016, and is expected to cost more than £10 million.
A spokesman for Gareth Hoskins said: "We and our wider team are excited at the opportunity of working with the National Galleries to create new spaces for their fantastic collection of Scottish art as part of the ongoing evolution of one of Edinburgh and Playfair's most significant groupings of cultural buildings."
Gareth Hoskins Architects has studios in Glasgow and Berlin and has worked on the Mareel Concert Hall in Shetland and the RIAS Doolan Award-winning redevelopment of the National Museum of Scotland.
Michael Clarke, director of the Scottish National Gallery said: "The outstanding collection of Scottish Art held at the Scottish National Gallery has an international significance.
"This transformational project will allow for the creation of new and innovative displays to inspire our growing number of visitors from all over the world."
Designed by the architect William Henry Playfair (1790-1857), the Royal Scottish Academy and the National Gallery of Scotland were originally built as separate structures.
Since the completion of the Playfair Project in 2004, they have been physically joined by the underground gardens entrance.