At 43.4%, turnout was the lowest ever, seven percentage points less than in the first round and 10 percentage points less than the previous record low.
French president Emmanuel Macron was poised to forge ahead with pro-EU, business-friendly reforms on Monday after his centrist party redrew the country's political map with a victory in parliamentary elections.
It is a stunning result for Mr Macron, after a presidential election that saw the collapse of both the two traditional main parties.
The conservative Les Republicains may now have nearly half the seats they had before, but with 137 MPs, they are still a force to be reckoned with.
The Socialist party was the biggest loser, expecting to shed more than 200 seats and hold only around 34 seats - again, better than forecast, but still a drubbing. Leader Jean-Christophe Cambadelis immediately resigned, nd called on the party to reform itself in the wake of the loss.
The huge majority shows the success of Macron's new party, which did not exist just 16 months ago. Now it is set to dominate legislation and win a vast injection of subsidies.
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Prime Minister Edouard Philippe, the rightwinger chosen by Macron to lead the cabinet, said voters had chosen "hope over misery". He added: "Abstention is never good news for democracy and the low turnout meant the government had "an ardent obligation to succeed".
"Macron's overwhelming majority should confirm already constructive sentiment", Commerzbank analysts said in a note. The percentage of women has climbed from 27 to 39 percent, although the key government functions remain firmly in male hands.
"For the first time under the Fifth Republic, the National Assembly will be profoundly renewed, more diverse, younger, with many professional, community and political backgrounds", Catherine Barbaroux, the interim president of En March, said in a speech following Sunday's vote.
The National Front won 8.75 percent of the votes nationwide, which is more than the Socialists and Melenchon's far-left party, yet it has less seats.
Le Pen entered parliament for the first time in her career in one of at least eight seats won by the FN, but the party fell well short of its 15-seat target. The low number of MPs means the FN can not set up a parliamentary group and benefit from funding. It will be a major blow to the party, which pollsters thought could claim as many as 50 seats when Le Pen made it through to the final of the presidential vote.
Le Pen said: "The abstention rate considerably weakens the legitimacy of the new parliament ..."
"Even if we don't know the new faces it's not important".