The project will see Willmott Dixon’s fit-out division enhance facilities at the world-famous gallery on Trafalgar Square.
Working with the architect Purcell, it involves the complete refurbishment of Room 32, the largest within the National Gallery, as well as refurbishing parts of the existing basement and ground floor areas.
Work will be completed in summer 2020.
It is the latest major landmark in London that Willmott Dixon Interiors has been appointed to transform and is also the second major cultural attraction in three years.
In 2016, Willmott Dixon Interiors completed work to refurbish the Grade 2 listed vacant Commonwealth Institute building and create a thriving new home for the Design Museum.
Willmott Dixon Interiors managing director Graham Shaw said: “We’ll be able to use our track-record of transforming historic buildings, such as the Commonwealth Institute, for the benefit of the National Gallery.
“Our team are really looking forward to enhancing another London landmark so that it can be enjoyed by millions of people over the coming years.”