Emmanuel Macron, the 39-year-old former banker who quit the Socialists for a remarkable tilt for France's presidency, has won the country's first-round vote, finishing just ahead of far-right candidate Marine Le Pen.
The French Interior Ministry's final figures for the vote showed Macron winning 23.75 per cent of the vote, with Le Pen on 21.5.
Francois Fillon for the Republicans, the party of the Gaullist establishment, came third with 19.9 per cent of the vote, just ahead of far-left firebrand Jean-Luc Melenchon with 19.6 per cent.
Macron is predicted to beat Le Pen far more comfortably in the second round of voting on May 7, by gathering the lion's share of voters from the eliminated candidates.
The absence of either of the country's major parties - the Republicans and the ruling Socialists - in next month's run-off vote has shocked the political establishment.
France faces a choice between a charismatic pro-Europe liberal centrist, and a charismatic anti-Europe illiberal populist.
Le Pen, 48, said this was a historic opportunity to choose between "savage globalisation that threatens our civilisation", and "borders that protect our jobs, our security and our national identity".
She told France, shocked by Thursday's shooting of a policeman on Paris' Champs-Elysees, that she would stop "mass immigration and the free movement of terrorists".
She intends to renegotiate France's relationship with the European Union, and hold a referendum on reintroducing the French franc.
Macron said the vote had "changed the face of this country [and] opened the door to optimism, a new path for hope for Europe and for the world".
"We heard the doubt, the anger, the fear of the people of France - they wanted change so badly. That's why tonight the two major parties who have governed France for three decade have been discarded."
After Thursday's shooting, he had begged voters: "Do not surrender to fear."
An Ipsos poll on Sunday evening predicted Macron would beat Le Pen in the second round by 62 per cent to 38 per cent.
Both the Socialist and the Republican candidates have asked their followers to vote for Macron in the run-off vote in two weeks' time.
Fillon warned Le Pen would lead the country into bankruptcy, chaos, violence, extremism and division. "Reflect on your conscience," he said.
The result is a new high-water mark for Le Pen's National Front.
The last time the National Front made the second round, in 2002, Le Pen's father, Jean-Marie, won just under 17 per cent of the first round vote.
He was crushed in the second round by Jacques Chirac, but his daughter is expected to do significantly better.
At the last election, in 2012, Marine Le Pen won 18 per cent of the first round vote, and did not make the second round.
Macron set up his En Marche! (Forward!) political movement just a year ago, while the youngest minister of the economy in the nation's history.
He framed himself as a centrist who wanted the economy more business friendly, in a liberal society.
His rivals attacked his centrist policies as vague crowd-pleasers, and tried to pin him down as the successor to Francois Hollande, France's most unpopular president in living memory.
Satirists portrayed him as the "unaccompanied child" of the campaign. Socialist candidate Benoit Hamon won just 6 per cent of the vote.
The vote was conducted under unprecedented security measures, following Thursday's attack, which was claimed by Islamic State although the gunman's link to IS remains uncertain.
More than 50,000 police officers and 7000 soldiers were deployed to polling stations across the country.
Nice, the site of a horrific terror attack last year, deployed its own security agents as back-up for police at its 252 voting stations.
France's faltering economy, its future in the European Union, security against terrorism and the level of immigration were the dominant issues in the campaign.
Both Le Pen and Melenchon campaigned against the EU, while both Le Pen and Fillon were vocal on the need for tighter immigration controls and a security crackdown.
Le Pen voted at the Jean-Jacques Rousseau school in Henin-Beaumont, a town in north-west France and the heartland of northern National Front support.
The town is ringed by huge black pyramids of barren industrial slag - imposing symbols of its lost industrial heritage as a coal mining centre.
"I voted for Marine Le Pen, for change," said local Reynald, emerging from a Henin-Beaumont polling station.
"There needs to be change in the economy, on immigration, all together. I am sick of the old politics of the left and right.
"I don't agree with all her ideas, but we have to have change."
But Le Pen posters were defaced across the town, with big strips torn off them in an attempt to hide their message.
Even at the centre of her support base, she still arouses strong opposition - sentiments that Macron is expected to harness in the coming fortnight.
Fillon tweeted that the fight against Islamist terrorism must be the priority of the next president, saying "we are at war, there's no alternative, it's us or them".
And Le Pen published a slew of tweets advocating her policies on restricting asylum for refugees and citizenship for immigrants. She also demanded the immediate expulsion of all foreigners on the terrorism watch list.
However, the Paris attacker last week, Karim Cherufi, a convicted criminal, was born in Paris and was not on the terrorism watch list.
Prime Minister Bernard Cazeneuve attacked Le Pen for "exploiting fear and emotion for political ends".
The New York Times cited research from previous Israeli elections that showed a terrorist attack close to an election could boost the right wing vote by a couple of per cent.
