French President Emmanuel Macron's centrist party scored a decisive victory after the second round of parliamentary elections, the Interior Ministry announced.
With 97 per cent of the votes counted by Sunday night, Macron's La Republique En Marche (LREM) party won 300 seats in the 577 National Assembly.
Its political ally, the Mouvement Democrate (MoDem) won 41 seats in the polls held earlier on Sunday.
The result has given 39-year-old Macron one of France's biggest post-war majorities, strengthening his hand in implementing his business-friendly, pro-EU programme.
But turnout was estimated to be extremely low, at around 44 per cent, giving his critics grounds to claim he has no groundswell of support.
The assembly is set to be transformed with a new generation of lawmakers—younger, more ethnically diverse and with far more women than the outgoing parliament.
The scale of the change is forecast to be so large that some observers have compared the overhaul to 1958, the start of the present presidential system, or even the post-war rebirth of French democracy in 1945.
Just months ago, Macron was given little chance of becoming president, never mind dominating parliament, but he and the movement he founded 16 months ago have tapped into widespread desire for wholesale change.
His party dominated France's traditional parties, the rightwing Republicans and Socialists, but also the far-right National Front (FN) of defeated presidential candidate Marine Le Pen which fell far short of its target.
The Socialists were the biggest losers of the night, punished by association with years of high unemployment, social unrest and lost national confidence.
The party lost around 200 seats after five years in power under former president Francois Hollande, leaving them with only around 27 to 49 seats.
The Republicans hung on to between 97 and 130 seats, down from over 200 in the last parliament, and remain the main opposition party.
Le Pen's FN were only expected to win four to eight seats but she was elected an MP.
But despite the zest for political renewal, the vote failed to generate much excitement.
Official statistics showed turnout at a near 60-year low, revealing a high degree of election fatigue after four votes in under two months.
"People are tired of always seeing the same faces," said Natacha Dumay, a 59-year-old teacher voting in the northeastern Paris suburb of Pantin where Socialist former justice minister Elisabeth Guigou was voted out a week ago.
"Even if we don't know the new faces it's not important. We're not voting for individuals but for a programme," Dumay added.
Turnout will be closely watched after it hit a near 60- year low in the June 11 first round of voting, leading some to warn Macron that his mandate is not as strong as he thinks.
REM won 32 percent of the votes cast in the first round, but this represented only about 15 percent of registered voters.
"Go and vote!" Prime Minister Edouard Philippe urged on Thursday, calling it both "a right and a responsibility".
Around half of REM's candidates are virtual unknowns drawn from diverse fields of academia, business or local activism. They include a mathematician, a female bullfighter and a former Rwandan orphan.
The other half are a mix of centrists and moderate left- and right-wing politicians drawn from established parties including ally MoDem.
Le Pen's victory was a rare bright spot for Le Pen's nationalist and anti-EU party which was once hoping to emerge as the principal opposition to Macron but is now expected to have only a handful of lawmakers.
The hard-left France Unbowed is also struggling to maintain the momentum it had during the presidential election.
