PARIS — Emmanuel Macron, a former investment banker, won France’s presidential election in a landslide Sunday, defeating nationalist Marine Le Pen as voters firmly rejected her far-right message and backed his call for centrist change.
Macron, 39, who has never held elected office, will become the youngest president in the 59-year history of France’s Fifth Republic after leading an improbable campaign that swept aside France’s establishment political parties.
The election was watched around the world for magnifying many of the broader tensions rippling through Western democracies, including the United States: populist anger at the political mainstream, economic insecurity among middle-class voters, and rising resentment toward immigrants.
Macron’s victory offered significant relief to the European Union, which Le Pen threatened to leave. His platform to loosen labor rules, make France more competitive globally, and deepen ties with the European Union was also likely to reassure global financial markets jittery at the prospect of a Le Pen victory.
Her loss provided further signs that the populist wave that swept Britain out of the European Union and Donald Trump into the White House may have crested in Europe, for now.
Macron’s victory marked the third time in six months — after elections in Austria and the Netherlands — that European voters shot down far-right populists who wanted to restore borders across Europe.
The election of a French president who championed European unity could also strengthen the EU’s hand in its complex divorce proceedings with Britain.
Macron takes charge of a nation that, when Britain leaves the union in 2019, will become the EU’s only member with nuclear weapons and a permanent seat on the UN Security Council.
“It is a great honor and a great responsibility,” Macron said, using a video link to address thousands of flag-waving supporters who gathered on the plaza of the Louvre, where he held his victory celebration. “A new page is opening.
‘‘I know the divisions in our nation that led some to extreme votes. I respect them,’’ he declared. ‘‘I know the anger, the anxiety, the doubts that a large number of you also expressed. It is my responsibility to hear them.’’
With about 90 percent of votes counted, Macron had 64 percent, the Associated Press reported. Le Pen had 36 percent — about double what Jean-Marie Le Pen, her father and cofounder of their far-right National Front party, achieved at the same stage in the 2002 presidential election. About 65 percent of the voters went to the polls.
The outcome gave the National Front new legitimacy, even as the results showed that the party remains anathema to much of the French electorate for its history of anti-Semitism, racism, and Nazi nostalgia.
After results were announced, Trump tweeted congratulations on what he called Macron’s ‘‘big win’’ and said he looked forward to working with the French leader.
Macron has said he wants to continue intelligence-sharing with the United States and cooperation at the United Nations and hopes to persuade Trump not to pull the United States out of a global accord fighting climate change.
Macron has also promised a France that would stand up to Russian President Vladimir Putin but that also would seek to work with Putin on fighting the Islamic State, whose extremists have claimed or inspired multiple attacks in France since 2015.
France has been in a state of emergency since then and 50,000 security forces safeguarded Sunday’s vote.
The runoff election was groundbreaking for being a choice between two political outsiders, as well as for its rancor and an apparent attempt to sway the vote with the large-scale hacking of Macron campaign e-mails, similar to the attack directed at last year’s election in the United States.
But although Macron won by a wide margin, the share of votes that went to Le Pen and the high abstention rate — the worst turnout since 1969 — indicated the challenges he faces in building a base of support for his program.
Le Pen conceded the election not long after polls closed in France, saying voters had chosen “continuity,” denying Macron his outsider status and linking him to the departing Socialist government, in which he served as economy minister.
The vote was a record for the National Front and, she said, a mandate for it to become a new “patriotic and Republican alliance” that would be “the primary opposition force against the new president.”
She added that the new political divide would be between “patriots and globalists” and that her party would transform into a new political force reflecting all those who voted for her.
The election was also the first in which the National Front candidate, rather than being a pariah who was shut out of debates and kept off the front pages of major newspapers, as happened in 2002, was treated more like a normal candidate.
Still, Le Pen clearly failed to convince a decisive portion of voters that her party really had changed. Many of the votes Macron received Sunday appeared to be cast not so much in support of him but in rejection of Le Pen.
Macron formed his political movement, En Marche! (Onward!), a little more than a year ago.
He was initially given a slim chance of winning in a country that has never elected a president from outside the traditional parties, the Socialists on the left and the Republicans on the right.
Macron’s campaign benefited from excellent timing and no small dose of luck, with the collapse of the governing Socialist Party under President Francois Hollande, the incumbent, who was so unpopular that he took the extraordinary step of not seeking reelection.
Macron received another strong boost from an embezzlement scandal that damaged the candidacy of center-right candidate Francois Fillon, who at the start of the campaign seemed certain to claim the presidency.
Macron has already started trying build support in Parliament, where he has no party to support him.
His message — that his new movement is neither right nor left, but represents a third way, with elements of both — seemed to have appealed to numerous urban voters as well as to many young voters.
As the results appeared on a screen set up at the Louvre, Macron supporters shouted with joy. Some started singing the Marseillaise, the French national anthem.
For Mourad Djebali, 30, a Tunisian engineer who obtained French citizenship a few months ago, the result felt like a personal affirmation.
“I’m moved,” Djebali said. “I recognize the France that has received me.’’ (Boston Globe)