The Atlantic Canada Opportunities Agency says the money will be used to repair an improve the Lunenburg Academy, a former school that first opened in 1885.
The agency says the building, known locally as the "Castle on the Hill," will be altered to create space for culture-related businesses and organizations.
When the school closed in 2012, the national historic site was taken over by the Town of Lunenburg.
The town is contributing $180,000 to the project and another $150,000 will come from the Lunenburg Academy Foundation.
The restoration of the building started last April when Ottawa spent $64,000 on exterior repairs.