Garcetti said utilizing the city's existing sports venues would keep costs down while ticket and sponsorship sales would top current projections to help Los Angeles avoid the pitfalls that have left some other host cities in debt.
"We made a million dollars in 1932, we made $250 million in 1984," he said, referring to the last two times the city has hosted the Games.
"I think we will make at least a billion dollars in 2028."
Garcetti said the money would help support youth sports in the city "for decades to come."
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"We've had cities scared to bid for the Olympics because they cost so much and because people build so much infrastructure for two and a half weeks.
"It wasn't a very sustainable model ... we created a different model."
Speaking to Reuters on the sidelines of the LA Sports Summit, Garcetti also said that seeing the deals Tokyo 2020 organizers had been able sign for sponsorships for next year's Games had made him even more bullish on his city's prospects.
"When I look at what other cities have been able to do in terms of sponsorships, we should be able to blow way past the guaranteed level that we're budgeting with," he said.
"I think our ticket sales will do that as well."
Garcetti's comments came on the same day the Los Angeles Sports Council released an 'Economic Impact Analysis of the Sports Industry in the Greater Los Angeles Region'.
The report found that last year alone the sports industry generated $6.3 billion in economic impact, $327 million in taxes for state and local governments while supporting nearly 40,000 jobs.
Los Angeles is home to 11 professional sports franchises and will next year open a multi-billion dollar NFL stadium in Inglewood, one of the venues that will host events in 2028.
(Editing by Peter Rutherford)
