The result, based on official figures and pollster projections, redraws France’s political landscape, humiliating the Socialist and conservative parties that alternated in power for decades until Macron’s election in May.
Three pollsters projected that Macron’s Republic on the Move (LREM) and its Modem allies would win 355 to 365 seats in the 577-seat lower house, fewer than previously forecast.
They predicted the conservative Republicans and their allies would form the largest opposition bloc with 125 to 131 seats, while the Socialist Party, in power for the past five years, and its partners would secure 41 to 49 seats, their lowest ever in the postwar Fifth Republic.
Official figures with 90 seats still left to be decided showed LREM had already won its majority.
“This is an opportunity for France. One year ago no one would have imagined such a political renewal,” Prime Minister Edouard Philippe said in a statement.
Voter turnout was projected to be a record low at about 42 percent.
The high abstention rate underlines that Macron will have to tread carefully with reforms in a country with muscular trade unions and a history of street protests that have forced many a past government to dilute new legislation.
Government spokesman Christophe Castaner said it signaled voters “had not wanted to hand Macron a blank check.”
Nevertheless, the scale of victory gives the president, a pro-European Union centrist, a strong platform from which to make good on campaign promises to revive France’s fortunes by cleaning up politics and relaxing regulations that investors say shackle the euro zone’s second-biggest economy.
Victory for Macron, France’s youngest leader since Napoleon, marks the routing of the old political class.
Having never held elected office, he seized on the growing resentment toward a political elite perceived as out of touch, and on public frustration at its failure to create jobs and spur stronger growth, to win the presidency.
His year-old party then filled the political space created by the disarray within the Socialist Party and the Republicans, with Sunday night capping a sequence of events that a year ago looked improbable.