In late March, Valls declared his support for Macron rather than for the candidate of his own Socialist Party (PS), Benoit Hamon, who ended up eliminated in the first round of the presidential election.
Macron founded his En Marche, or "On the Move", movement barely a year ago, sweeping to a win in Sunday's presidential election with the help of voters fed up with establishment parties. That is largely down to the fact that markets were virtually certain of a Macron victory, and had priced it in accordingly.
"Happy that the French chose a European future", European Commission President Jean-Claude Juncker wrote on Twitter.
"I look very much forward to working with him", Trump tweeted.
"The citizens of France have trusted you with leading the country at a hard time for Europe and the whole world community".
While anti-establishment sentiment in France - which also characterised the UK's Brexit vote and the ascendance of Donald Trump to the USA presidency - was epitomised by Le Pen, Macron's win also marked a breakdown in traditional French politics. "The growing threat of terrorism and violent extremism goes hand in hand with the escalation of local conflicts and the destabilization of entire regions", Putin's message reads. "In these circumstances, it is especially important to overcome mutual distrust and unite efforts to ensure global stability and security", he said.
Canadian Prime Minister Justin Trudeau said he wanted to work together with Macron on a "progressive agenda" to "promote worldwide security, increase collaboration in science and technology, and create good, middle-class jobs on both sides of the Atlantic".
Joseph Downing, researcher at France's National Centre for Scientific Research, said that "when Macron declared he was going to run as a pro-globalisation, pro-EU candidate. people thought he was insane, and he has won".
In his first speech as president Sunday night, Emmanuel Macron said he had heard the "anger" and the "fears" of some of his compatriots, and promised that he would work to be an inclusive president.
Trump did not endorse any candidate in the election, though many believed he supported Le Pen after comments he made in April in apparent praise of the far-right candidate's tough stance on immigration.
According to polls released Monday, En Marche will win between 24 and 26 percent of votes in those elections, with the conservative Republicans party on 22 percent and the National Front on 21-22 percent. "I will do everything in the next five years so that they have no more reason to vote for extremes", he said. A key aide said the party would change its name as part of a revamp.