Conceding defeat, Le Pen told her supporters: "The National Front... must deeply renew itself in order to rise to the historic opportunity and meet the French people's expectations".
Emmanuel Macron has pulled off an extraordinary victory. "I will do all I can to be worthy of your trust and confidence", it quoted Macron as saying.
He quit his job as a banker at Rothschild to become Socialist President Francois Hollande's economic adviser, working for two years by Hollande's side at the presidential palace. He and Le Pen advanced to a runoff election after finishing first and second in an initial vote two weeks ago.
Macron had an unexpected test of his political skills last week during what became known as "the battle of Whirlpool", when Le Pen upstaged him at a Whirlpool factory in Amiens that is threatened with closure.
Le Pen said she had called Macron to wish him success.
The president-elect's initial challenge will be to reconcile with the widespread nationalistic fervor that buoyed his opponent. Shortly after polls closed, Le Pen spoke to supporters, pledging a "profound reform" of her party, the National Front, in an effort to create "a new political force". Speaking after his victory, Macron promised to "fight the divisions" in the country.
Macron's victory is not a surprise as polls routinely showed him far ahead of Le Pen.
"I know the divisions in our nation, which led some to vote for extremist parties. I respect these", Macron said.
"I know the angers, the doubts, the anxiety that some expressed", he said. "It is my responsibility to hear these".
Britain had voted to leave the European Union six months before and the United States had just elected a president who was hostile to their grand project and the values it stood for. Almost 60% of those who planned to vote for him said they would do so to stop Ms Le Pen, rather than out of any enthusiasm for Mr Macron. Le Pen, the National Front's leader, achieved the party's best election result ever with proposals based on intolerance and xenophobia.
Le Pen's positions on national security and the admittance of refugees drew parallels to U.S. President Donald Trump.
Before the first round of the election last month, he said a deadly attack against a police officer in Paris would have a "big effect" on the vote and he praised Le Pen on immigration, calling her "the strongest on what´s been going on in France".
"Congratulations to Emmanuel Macron on his big win today as the next President of France", Trump tweeted.
The White House on Sunday also issued a formal statement congratulating "Macron and the people of France on their successful presidential election".
Angela Merkel: German Chancellor Angela Merkel in a tweet said that Macron's win is a victory for Europe.
"I was thinking perhaps that he had the idea of running away", Le Pen said sarcastically. The former investment banker is an advocate of free market economics and his ardent support of the European Union was a tenet of his campaign.
Former US president Barack Obama who openly backed Macron last week and whose message of hope served as a model for the French candidate is a cautionary tale for what can happen when some promises go unfulfilled.