The vote, in addition to setting the Olympic schedule for 11 years, breaks the IOC's tradition of selecting host cities one at a time.
Los Angeles Mayor Eric Garcetti signed the "host city contract" immediately after the International Olympic Committee vote, promising the city government will serve as a financial backstop to pay off any debts should the estimated $5.3-billion sporting event run over budget, according to the Los Angeles Times.
Paris, which has hosted two previous Olympics, will stage the event 100 years after its last Games in 1924 while Los Angeles will also organise its third Games after 1932 and 1984.
Paris was awarded the 2024 Olympics and Los Angeles the 2028 Games by the International Olympic Committee (IOC) on Wednesday, the first double allocation in nearly one century in reaction to several cities withdrawing their bids. Since then, France had made three unsuccessful bids for the Olympics.
Wasserman, mayor Eric Garcetti and U.S. Olympic gold medalist Allyson Felix are presenting, as the IOC prepares to award 2024 to Paris and 2028 to LA later this afternoon.
The idea of the agreement came to light after a working group of IOC Vice-Presidents studied the possibility of a double allocation of the Olympic Games 2024 and 2028.
The two cities are getting the hosting rights without the usual dramatic vote. "We're two great cities, it's two great Olympic hosts and it's going to be two great games". In exchange for the compromise, LA will grab an extra $300 million or more that could help offset the uncertainties that lie ahead over an 11-year wait instead of seven.
"We're ready now", Garcetti insisted, speaking of a city that has virtually every sports venue already in place.
Later, Paris mayor Anne Hidalgo stood by Bach's side and dabbed away tears as the vote was announced and the International Olympic Committee president handed the traditional - but now unneeded - cards to her and Garcetti.
The smooth finish to the race also eliminates the risk of the vote being tainted by the sort of scandal that has embroiled the ballot for the 2016 Olympics.
With a responsible and controlled budget, these Olympic Games will have an estimated economic impact of €10.7 billion for the period 2017-2034, according to a study by the Center for Law and Economics of Sport. "Both cities are very enthusiastic about the Games and are promoting the Olympic spirit in a fantastic way", Bach added.