The outcome severely tarnished Macron's April presidential election victory.
French President Emmanuel Macron on Sunday lost his parliamentary majority after major election gains by a newly formed left-wing alliance and the far right, in a stunning blow to his plans for major second term reform.
The result threw French politics into turmoil, raising the prospect of a paralysed legislature or messy coalitions with Macron forced to reach out to new allies.
Macron's "Together" coalition was on course to be the biggest party in the next National Assembly, but with 200-260 seats it will be short of the 289 seats needed for a majority, according to a range of projections by five French polling firms after Sunday's second round.
"Of course, it's a first place that is disappointing," government spokeswoman Olivia Gregoire told BFM television. "We're lower than we would have hoped."
The outcome severely tarnished Macron's April presidential election victory when he defeated the far-right to be the first French president to win a second term in over two decades.
The new left-wing coalition NUPES under 70-year-old hard-left figurehead Jean-Luc Melenchon was on course to win 149-200 seats, according to projections.
The coalition, formed in May after the left splintered for April's presidential elections, brings together Socialists, the hard left, Communists and greens.
The left only had 60 seats in the outgoing parliament, meaning they could triple their representation.
Far-right leader Marine Le Pen's National Rally party was also on track for huge gains after having only eight seats in the outgoing parliament.
It was due to send 60-102 MPs to the new parliament, according to the projections.
Macron, 44, had hoped to stamp his second term with am ambitious programme of tax cuts, welfare reform and raising the retirement age that is now in question.
"This will complicate the reforms... It will be much more difficult to govern," said Dominique Rousseau, professor of law at Paris Pantheon-Sorbonne University.
As president, Macron retains control over foreign policy, with the 44-year-old seeking to play a prominent role in putting an end to Russia's invasion of Ukraine.
'Disappointing first place'
Melenchon called Sunday's results "above all an electoral failure" for Macron. "The rout of the presidential party is total and there will be no majority," in parliament, he told cheering supporters in Paris.
A prominent MP from Melenchon's party, Alexis Corbiere, said the result meant Macron's plan to raise the French retirement age to 65 had been "sunk".
"The slap," said the headline in the left-leaning Liberation's Monday edition, adding the results represented the "fall" of Macron's way of governing.
Le Pen hailed a historic result for her party, saying it would send "by far" its highest number of MPs to the next National Assembly.
There could now potentially be weeks of political deadlock as the president seeks to reach out to new parties.
The most likely option would be an alliance with the Republicans (LR), the traditional party of the French right, which is on track to win 40-80 seats.
"We will work with all those who want to move the country forwards," Gregoire told France 2.
Economy Minister Bruno Le Maire denied that France would be ungovernable but admitted "a lot of imagination would be needed" from the ruling party in an "unprecedented situation".
Ministers at risk
The nightmare scenario for the president -- the left winning a majority and Melenchon heading the government -- appears to have been excluded.
But it was a dismal evening for Macron, who last week had called on voters to hand his coalition a "solid majority", adding "nothing would be worse than adding French disorder to the world disorder".
The ruling party's campaign had been shadowed by growing concern over rising prices, while new Prime Minister Elisabeth Borne failed to make an impact in sometimes lacklustre campaigning.
In another blow, key ministers standing for election were set to lose their jobs under a convention that they should resign if they fail to win seats.
Health Minister Brigitte Bourguignon was defeated by the far-right in the battle for her seat, while Maritime Minister Justine Benin lost her seat in the French Caribbean.
France's Europe Minister Clement Beaune and Environment Minister Amelie de Montchalin are facing tough challenges in their constituencies, with both set to exit government if defeated.
Two close Macron allies, parliament speaker Richard Ferrand and former interior minister Christophe Castaner, both acknowledged defeat in the fight for their seats.
Turnout was as forecast to be low, with polling institutes projecting an abstention rate of 53.5-54 percent, higher than the first round but not beating the record worst turnout of 2017.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)