Mittenaere, 24, edged out Miss Haiti, the first runner-up, and Miss Colombia the second runner-up.
In the final question round, Miss France highlighted the benefits of open borders when asked about the global refugee crisis.
"In France we want to have the most globalisation that we can. We want to have the biggest exchange of people that we can. Maybe someday that will change but now we have open borders," Mittenaere said.
Miss Kenya, another finalist, said Donald Trump's presidency "may not have been the choice of many people" and divided the United States.
She also spoke out in support of former US president Barack Obama and said she backed Hillary Clinton to be America's first woman president.
"I feel once he took up his position, he was able to unify the entire nation," said Mary Esther Were, 27.
Miss Colombia appeared to allude to Trump when asked why violence was prevalent in the world.
"Although there are presidents who don't get along with others, we work together to unite. Campaigns, respect and inclusivity to be able to have a social transformation that would educate our children," said Andrea Tovar, 23.
Monday's show was headlined by US performers including Grammy award-winning rhythm and blues group Boyz II Men and rapper and Grammy award nominee Flo Rida.
Pia Wurtzbach of the Philippines won last year following a major blunder in which the host -- Emmy Award winner Steve Harvey -- mistakenly awarded the title to Miss Colombia.
Harvey corrected the error minutes later, apologising on air to Wurtzbach and Miss Colombia, Ariadna Gutierrez.
Harvey this year got through the closing moments of the ceremony smoothly.
The Philippines agreed to host the pageant as part of efforts to draw tourists and investors.
Beauty pageants are also hugely popular in the Philippines, particularly among the tens of millions of poor who see the contests as a chance for their beautiful compatriots to live a life of fame and luxury.
But allowing the Philippines to host has proved controversial, with critics claiming the pageant would whitewash Duterte's brutal drug war, which has left more than 6,000 people dead.
Environmentalists also hit out at pageant organisers for letting the bikini-clad contestants swim last month with endangered whale sharks.
Despite the controversies, excited fans from across the globe lined up before dawn to watch the pageant, which was held in the morning Manila time for the coveted prime American evening viewing audiences.
Fans dressed in evening gowns with a sash took selfies outside the seaside arena where the competition was held while others organised viewing parties in hotels and restaurants in the capital.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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