Emmanuel Macron delivers a speech in front of the Louvre Museum in Paris, France, on May 7, 2017.
It was the first time the men had appeared in public together since Macron resigned in August past year as the French minister for the economy and finance to run for president - a decision that was received coldly by the French leader at the time, according to French media.
Despite losing to Mr Macron - securing just around 33.9 per cent of the vote compared with his 66.1 per cent - Ms Le Pen did almost twice as well as her father did when he reached the second round of the election in 2002, though she fell short of the 40 per cent party officials had said would be a success. The abstention rate for younger people was also much higher than that of older voters, revealing that fewer young people believed in either the threat of Le Pen or the globalist programme of Macron.
"I am more than relieved, I am delighted to see that Emmanuel Macron has won the election by a wide margin", Catherine Cesarsky, an astrophysicist at the CEA, France's atomic energy commission, told Nature News. "It is my responsibility to hear these".
On Europe, Macron said he would work to rebuild links between Europe and the people that form it. All 577 seats in France's National Assembly will be up for grabs.
He must also take care to remember that the troubles that Ms. Le Pen, as well as the far-left candidate Jean-Luc Mélenchon, emphasized in the election campaign are very real in France - youth unemployment, the continuing decay of aging industries and the tenuous assimilation of many Muslim immigrants, among them.
Marine Le Pen dances the night away after election loss
It is no secret that much was at stake, keeping in mind what Marine Le Pen, a fierce nationalist, was threatening to do. It is also time for Macron to unite his divided country and become leader also of those who did not vote for him.
The poll, for M6 television, also found Le Pen's supporters to be more convinced by their candidate's policies and qualities: 56% of Le Pen voters found she spoke to their concerns, while only 21% of Macron voters said the same of him.
Her tally was nearly double the score that her father Jean-Marie, the last far-right candidate to make the presidential runoff, achieved in 2002, when he was trounced by the conservative Jacques Chirac.
Outgoing French president Francois Hollande called Macron to congratulate his win, saying it marked French citizens' commitment to the European Union, and France's opening to the world.
French President-elect Emmanuel Macron has resigned from the presidency of his En Marche!
German chancellor's chief of staff Peter Altmaier said over Twitter Macron's success has sent a strong signal for "common values" and Franco-German ties.
Macron will name his prime minister and cabinet members next week.