The Assembly Hall was built in 1898 as a multipurpose building for the hospital. The main room on the second floor was used for dances, religious services, plays, etc.
The first floor also originally contained a store and an office for the storekeeper. A beauty parlour was added in the 1950s.
As with the rest of the hospital, the Assembly Hall was closed done in 1979 when the hospital was shut down. It remain closed for two decades.
In 2001 the building was reopened as a multipurpose hall operated by the City of Toronto. A grassroots group had been created a few years before to get the building reopened, originally by the Borough of Etobicoke (the City of Toronto after January 1998.) Various community groups now rent the Assembly Hall for their events.