The Royal Pharmaceutical Society has sold its headquarters building at the corner of Lambeth Road and Lambeth High Street.
The RPS, which has been based in SE1 since the mid-1970s, will move to East Smithfield in Wapping.
According to Property Week, developer Real Estate Resolutions paid around £15 million for the Lambeth building.
In a Q&A document published online, the RPS says that the new owner is expected to "create a new building for residential use, with ground floor retail space".
"I'm pleased to announce we have exchanged contracts on our new headquarters and also on our existing building in Lambeth," said RPS treasurer Sultan "Sid" Dajani.
"For over two years, my colleagues and I have been conducting a review of our overall estates strategy. We have always made decisions with the interests of our members and the society foremost in our minds."
The RPS will move out between October 2014 and May 2015.