President Emmanuel Macron is so far in the lead to win re-election over far-right rival Marine Le Pen with results predicted to be closer than in 2017.
France has prepared to choose between centrist President Emmanuel Macron and far-right challenger Marine Le Pen to rule the country for the next five years after a bitterly contested and polarising election campaign.
Saturday is marked by a campaign blackout, with no campaigning allowed and no more polls published. Some 48.7 million French are eligible to vote.
Macron is the favourite to win re-election in the run-off ballot on Sunday and there are indications he bolstered his advantage with a combative performance in the one-off election debate against a somewhat defensive Le Pen.
But the president and his allies have insisted over the last week that nothing is in the bag, with a strong turnout crucial to avoid a shock in France comparable to the 2016 polls that led to Brexit in Britain and Donald Trump's election in the United States.
Left-wing EU leaders including German Chancellor Olaf Scholz have pleaded with France to choose Macron over his rival.
The stakes are huge - Le Pen would become modern France's first far-right leader and first female president. Macron would be the first French president to win re-election in two decades.
Polls in mainland France will open at 0600 GMT on Sunday and close 12 hours later, immediately followed by projections that usually predict the result with a degree of accuracy.
Final campaign flurry
Voters in French overseas territories that span the globe start voting earlier, beginning with those in North America and the Caribbean on Saturday, followed by the Pacific and then the Indian Ocean.
The first to have their say in the election were voters in the tiny island territory of Saint Pierre and Miquelon off the northern coast of Canada who began casting ballots at 1000 GMT.
Macron and Le Pen threw themselves into a final flurry of campaigning Friday, firing off attacks in interviews before last-minute walkabouts and rallies.
Le Pen insisted that opinion polls giving Macron the lead would be proved wrong and took aim at her rival's plan to push back the retirement age to 65 from 62. Macron for his part said Le Pen was trying to mask an authoritarian "extreme right" platform.
Polls have shown Macron with a lead of some 10 percentage points. The highly anticipated TV debate did not change the trend and, if anything, allowed Macron to open more of a gap.
But analysts say abstention rates could reach 26 to 28 percent, with reluctant left-wingers needing to back the president for him to be sure of victory.
The result is predicted to be closer than in 2017, when the same candidates faced off but Macron carried the day with 66 percent to 34 percent.