Whitehall Museum in Cheam will re-open in 2018 after undergoing a £1.5 million revamp.
The historic building secured the grant from the Heritage Lottery Fund in 2015. Whitehall is believed to have been built around 1500.
Lib Dem Councillor and Leader of Sutton Council, Ruth Dombey, said: “The redevelopment will include work to the structure of the building and the installation of a new lift and stairs to improve accessibility, particularly for the disabled.”
Cheam Councillor Mary Burstow said: “The Friends of Whitehall group and the Council did an excellent job securing the funding to make this happen.
“We’re all looking forward to Whitehall re-opening. It’s one of the borough’s heritage gems.”
A programme of events and activities for children, families and the local community will be revealed before the re-opening.