The 45,000-square-foot building — which was previously occupied by a bank — had a final price tag of $8.05 million.
The city plans to make the switch in early 2018 after making minor modifications to the building. It will provide office space for city staff, the police department, municipal court and city council chambers.
Mayor Denis Shortal, who signed the closing documents with city manager Eric Linton, said it was a great day for all Dunwoody residents.
"We are the very proud owners of our own City Hall,” said Shortal in a news release. “We purchased a fantastic building situated in a central location to serve the residents and businesses of our city.”