Dementia-Friendly Alton will be the new leaseholder at the Assembly Rooms.
There had been uncertainty over who would run the historic venue from the start of next year.
Current leaseholder the Alton Community Association had decided to concentrate on Alton Community Centre and an agreement with the Whitehill & Bordon Town Partnership to turn the Assembly Rooms into a performing arts hub collapsed because of funding issues.
Dementia-Friendly Alton had intended to make its home at Edgar Hall, the former St John Ambulance headquarters in Anstey Park. But problems with a planning application to extend the hall forced the charity to look elsewhere for a permanent base.
It will take over the Assembly Rooms lease on January 1 but will remain at Edgar Hall until March 31. It plans to use those three months to make improvements to the kitchen, changing rooms – which would host wellness sessions – and toilets at the Assembly Rooms.