As Le Pen continued to celebrate the highest-ever voting tally for her National Front party, French President François Hollande joined candidates knocked out in the first round in endorsing Macron, who ended his insurgent campaign with a result that confounded expectations.
Both go through to a runoff on May 7 after emerging top of a fractured field of 11 candidates in the first round.
The result amounted to a comprehensive rejection of traditional politics in France. It is the first time since the establishment of the fifth French Republic in 1958 that no candidate from the two main political parties of the left and right has made it into the second round of the presidential vote.
Macron goes through to the second round as the clear frontrunner, with most voters expected to switch to him from mainstream defeated candidates. Le Pen, meanwhile, faces an uphill struggle.
The French stock markets rose on Monday morning, and the euro jumped to its highest level since Novembe
r against the dollar as investors bet against the chances of Le Pen winning.
There was relief in Europe, too: Michel Barnier, the European Union's chief Brexit negotiator, described Macron as a "patriot."
The chief of staff for German Chancellor Angela Merkel said the result showed France and Europe could "win together" and added: "The center is stronger than the populists think."
Hollande -- whose ratings have been in the doldrums for several years now -- said on Monday he would vote for Macron.
"(Macron) will allow all the French to come together, to rally around in this most precarious difficult moment of the history of France."
He added that voting for Macron would signify unity in the country and an acceptance of France's place in the world and its role in Europe. A vote for Le Pen would be a "risk," he said.
, the mainstream Republican candidate whose campaign foundered amid corruption allegations, emerged swiftly from his defeat with words of support for Macron.
"I promise you, extremism can only bring unhappiness and division to France," he said, describing the National Front as a party of "violence" and "intolerance."
"We have to choose what is preferable for our country, and I am not going to rejoice. Abstention is not in my genes, especially when an extremist party is close to power," he said. "There is no other choice but to vote against the far right."
He argued that Le Pen's economic and social programs would bankrupt the country, particularly if France dropped the euro as its currency, as the far-right leader has threatened.
The Socialist Party's candidate, Benoit Hamon, also warned against a Le Pen victory. "I appeal to you in the strongest terms to beat the National Front by voting for Emmanuel Macron, even though he is not part of the Left," Hamon wrote on Twitter.
Hamon secured just 6.4% of the vote, a disastrous showing for the Socialist Party, whose candidate Hollande won the presidency in 2012 but whose popularity has sunk during his term.
French Prime Minister Bernard Cazeneuve tweeted his support for Macron, calling on voters to back him in the second round "to combat the National Front's disastrous project to take France backwards and to divide the French people."
But far-left candidate Jean-Luc Melenchon has refused to say who he would back, criticizing both candidates for having "no stance on the environment or the future of civilization, and who both challenge the welfare and social accord of the country."
France: Open or closed?
French voters made it clear Sunday that they were ready for change -- neither candidate hails from the establishment parties that have dominated the country for decades.
In the next two weeks, Macron will build on his pro-European, centrist message while Le Pen made it clear she would intensify the nationalist, anti-Islamist rhetoric that propelled her into the second round.
Sunday's first round contest was held under tight security after a terror attack in Paris Thursday night
disrupted the final day of campaigning Friday. And the Paris attacks in November 2015, in which 130 people were killed, saw Hollande's popularity plunge into the doldrums.
Le Pen, 48, told supporters her first move as president would be to impose a temporary ban on legal immigration to France. She has also vowed to take France out of the EU.
"The French people must seize this opportunity, because the enormous challenge of this election is the wild globalization that puts our civilization at risk," Le Pen said at Henin-Beaumont, a National Front stronghold in northern France.
"Either we continue to disintegrate without any borders, without any controls, unfair international competition, mass immigration and the free circulation of terrorists, or you choose France with borders," she added.
Le Pen said on Twitter Monday she is taking a leave of absence as leader of the National Front party to focus on the election campaign.
"I am nothing other than a candidate for the French presidency," she said.
Macron, 39, has warned against nationalism and has attracted support from the left and right for his more moderate stance, promising to boost the economy and improve security.
"I will be the president of the patriots against the threat of the nationalists. There is only one France, France of the patriots in a protective Europe. The fight to be trustworthy to run our country starts tonight and we will win it," he said Sunday night.
His party, "En Marche!" which was only created in September, now has more than 200,000 members and his meetings have attracted vast crowds.
Le Pen, Macron supporters rejoice
Le Pen's advancement to the second round is not without precedent -- her father, Jean-Marie Le Pen, made it to a runoff against the then-incumbent Jacques Chirac in 2002, only to suffer a devastating loss
when anti-extremist voters rallied against the National Front leader.
But it was not the comprehensive breakthrough for the far right that some had predicted.
Nonetheless, supporters at the National Front's headquarters responded to the results with songs and dance through the night, waving Le Pen flags.
"Marine Le Pen -- liberty!" shouted supporter Lilie Bultez.
"Immigrants, terrorism, killing police officers -- I can't bear it. I don't want to see that kind of thing anymore. I want to live in a free country," she told CNN.
A huge cheer erupted at Macron's headquarters after the results emerged, his supporters waving the French Tricolour flag, and those of the EU.
"I'm actually quite happy because I voted Emmanuel Macron yesterday," Roman Maison, a 27-year-old banker, told CNN in Paris on Monday.
"I think it's a big great message for Europe, this is a great message for all around the world that populists are not winning."
The result mirrored others -- such as the British vote to leave the European Union and the US election of Donald Trump -- where voters have rejected traditional elites.
"It's a political earthquake in this country and in Europe," veteran French journalist Christine Ockrent told CNN.
Fillon was an early favorite for the presidency, but his campaign suffered from allegations that he paid his wife and children for work they never carried out. He denies any wrongdoing.
Far-left firebrand Mélenchon
, whose popularity surged in the final weeks of the race following impressive performances in the television debates, has so far refused to concede defeat, but said he would accept the final results when they came in.
"We do not recognize the score announced on the basis of opinion polls," he wrote on Facebook
. "The results of the larger towns and cities are not yet known," he added, calling for "restraint" and urging commentators to "be cautious."
Fillon came in third with 20.01% of the votes and Melenchon followed him with 19.58%.