Due to Bottoms less than 1 percent victory margin, Norwood immediately called for a recount of the vote once the results were announced.
Acknowledging this history, Norwood said, "I've done this before".
Bottoms' victory makes her the second Black woman to hold mayoral office in Atlanta.
Norwood, who trails behind front-runner Keisha Lance Bottoms by just 759 votes after Tuesday's election, was bested by current mayor Kasim Reed in a 2009 runoff by only 714 votes.
Atlanta's last white mayor, Sam Massell, left office in 1974 and was succeeded by five African-American mayors in the next four decades: Jackson, Andrew Young, Bill Campbell, Shirley Franklin and Reed.
His tenure as mayor became one of the major factors in the race.
"In the eastern part of Atlanta you see a good deal of gentrification going on, and you see a mix of precincts - some for Norwood and some for Bottoms", Boone said.
Democratic Party of Georgia chief Dubose Porter told the crowd Bottoms was "beyond being the most qualified person in the race".
Norwood also got endorsements from several of her former competitors, and state senator Vincent Fort - the unsuccessful candidate backed by independent Sen.
Polls have closed in a runoff election between two Atlanta councilwomen vying for the city's top job.
UPDATE: An earlier version of this story, citing information from Fulton County, said a recount was set to take place on Saturday.