The two cities originally bid to host the 2014 Olympics, but Paris won and LA will be given four more years to prepare for the event under an agreement worked out with the IOC.
IOC President Thomas Bach described the decision as a "win-win-win" for all three parties involved.
"Congratulations to Paris 2024 and Los Angeles 2028! This historic double allocation is a ‘win-win-win’ situation for the city of Paris, the city of Los Angeles and the IOC," Bach said.
The Paris 2024 Olympic and Paralympic Bid Committee issued a statement saying "the decision is the climax of a two-year journey that has seen the Paris 2024 team assemble and promote a stunning, innovative Games plan".
French President Emmanuel Macron congratulated in a televised statement the team of the Paris 2024 Committee. "For the next seven years, we will be preparing for these Olympic Games. It will be the games of Paris, of course, but the whole country must be mobilized," he said.
"We will have to work with the athletes, in terms of safety, environment, and financial commitment. But these games are yours, this victory is yours and we will ensure that Paris hosts magnificent games. So bravo!" he added.
-Back to Paris after 100 years
Paris 2024 Bid co-chair Tony Estanguet called the decision "a wonderful moment for the people of Paris and France and also the Olympic Movement".
"The Games are coming to Paris for the first time in 100 years and we will deliver an amazing celebration of sports at the heart of one of the world's greatest cities," he said.
Mayor of Paris, Anne Hidalgo also celebrated what she called "a historical moment", and a "victory that will be a real accelerator of ecological transition, job creation and solidarity".
"They are the confirmation of a positive future for our youth, Hidalgo said. "Let's be proud! When Paris takes up the challenges of the 21st century, it is all of France that wins".
To celebrate the historic decision, a statue of the Olympic Rings was erected at the Trocadero Square, just in front of the iconic Eiffel Tower. The Rings will remain in place until Sunday, before they travel around the city for the people of Paris to enjoy, according to the Committee.
Mayor of Los Angeles, Eric Garcetti said that bringing the Olympics back to LA "gives us the chance to imagine what our city will look like a decade from now".
"LA is a city where the Games are not a barrier to making progress; we know that they are an accelerating force to re-envisioning a better city and a better world in the days ahead as we welcome you back to the City of Angels."
Paris last hosted the games in 1924 and lost bids for the games in 1992, 2008 and 2012. For Los Angeles, it will be the third time it hosts the summer games after 1932 and 1984.
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