Beaten candidates such as Socialist Benoit Hamon and conservative Francois Fillon were quick to give their support to Macron for the second round in an attempt to block the anti-EU Le Pen from winning on May 7.
Fillon won 19.9 percent of the vote, close to the 19.4 percent for extreme-left candidate Jean-Luc Melenchon, who did not immediately lend his support to Macron for the runoff.
Speaking to his supporters in Paris at what he called an "unprecedented moment in its history," Macron said that in bringing En Marche to life over the last year "we have changed the face of French political life."
A former investment banker, Macron had served as economy minister in the government of President Francois Hollande before forming his own "Association for the Renewal of Üolitics," the official name of En Marche, in April 2016.
Macron said the challenge was to remedy a political system that had been unable to solve problems over the past 30 years and to create a new political landscape for France and for Europe. He promised to bring new faces and new talent into French politics.
In clear reference to his far-right opponent, Macron said: "I want to be the president of patriots against the threat of the nationalists." "I want to talk to all citizens in France. I know your expectations," Macron told his supporters.
Macron has no "En Marche!" parliamentary representatives and just 14 candidates standing for the June legislative elections, although the figure is expected to rise.
Le Pen celebrating
Speaking in her constituency Henin-Beaumont in northern France, Le Pen thanked her supporters for bringing her to the second round, calling it a historic result.
She suggested that "the French people now have a very simple choice: either we continue on the path to complete deregulation, or you choose France."
Claiming to be the candidate of the people, Le Pen said "it is time to liberate the French nation from arrogant elites who want to dictate how it must behave."
Le Pen has proposed holding a referendum on France's membership of the EU, limiting immigration, increasing control on the country's borders and expelling Islamic extremists.
Opposition support for Macron
Support for Macron to prevent Le Pen gaining the presidency came quickly from some defeated candidates. Francois Fillon said Le Pen's "Front National is well known for its violence and its intolerance, and its program would lead our country to bankruptcy and Europe into chaos."
"I will vote for Emmanuel Macron. I consider it my duty to tell you this frankly. It is up to you to reflect on what is best for your country, and for your children," Fillon told his supporters. Party veteran Alain Juppe gave a similar message at the rally saying, "Without hesitation I support Macron in his duel with the FN, who would lead France to disaster."
Defeated socialist candidate Benoît Hamon was joined by the party's Bernard Cazeneuve, the current prime minister, in encouraging support for Macron. "I solemnly call for a vote for Emmanuel Macron in the second round in order to defeat the Front National and block the disastrous project of Marine Le Pen that would take France backwards and divide the French people,” he said. Hamon polled only 6 percent of the vote.
New opinion polls
Opinion polls published on Sunday gave Macron a large lead for the second round. A Harris survey taken on Sunday indicated Macron would win by 64 percent to 36 percent for Le Pen. An Ipsos/Sopra Steria poll returned a similar result.
Reaction on financial markets overnight also indicated positive reaction to the result. The euro rose 2 percent to $1.09 when markets opened in Asia before slipping back to around $1.08, reaching what was the euro's highest level since last November, the day after the results of the US presidential election.