Ziser London is to buy the Grade II listed site from a private vendor using a £10m loan from OakNorth bank.
It will seek planning permission to convert the 51,350 sq ft property in to a hotel, restaurants, event space and spa, while preserving its original features.
The building was constructed in 1888-1890 and originally functioned as a traditional Town Hall, but has been used as a registry office and for events following the merger of the boroughs of Hammersmith and Fulham in 1965.
Debt advisor and asset manager BBS Capital arranged the loan with OakNorth, which has previously backed restaurant groups including Daisy Green, Leon and Brasserie Bar Co.
“Once completed, this site will be a landmark property in London, so we’re delighted to be assisting the team and look forward to working with them on additional projects in the future," says Priya Harley, debt finance director at OakNorth.
OakNorth also provided £10m funding to the Inn Collection Group, which runs nine pubs across Northumberland, last month.