Projections show Macron's LREM and its Modem allies winning 400-445 out of 577 seats in the National Assembly.
That would give the new president one of the biggest parliamentary majorities for 60 years.
Official final results released early Monday showed:
- Macron's LREM and François Bayrou's MoDem winning 32.32 percent;
- The mainstream right Republicans on 21.56 percent;
- Jean-Luc Mélenchon's radical left France Unbowed and the Communists on 13.74 percent;
- The far-right National Front on 13.20 percent,
- The Socialists and their allies secured just 9.51 percent.
"France is back," Prime Minister Edouard Philippe declared. "For the past month the president has shown confidence, willingness and daring in France and on the international stage."
But 51 percent of potential voters did not make it to the polling booth, casting a shadow over the celebrations.
Recognising that the poor turnout was a "failure", government spokesman Christophe Castaner promised that the new government would work to provide solutions to French people's everyday concerns.
"We have to hear [the discontent], we have to restore confidence," he said.
With candidates with lower votes eliminated in the first round, the second round will pitch the top two candidates - or in just one case the top three - in a final battle to win parliamentary seats.
Projections show the right-wing Republicans trailing LREM, with Jean-Luc Mélenchon's France Unbowed and its Communist allies becoming the main force on the left, although with fewer seats than they had hoped, replacing a humiliated Socialist Party.
The far-right National Front also looks set up its share of parliamentary seats but will probably not win enough to form a parliamentary group.
Above all, the new National Assembly is likely to be made up of political novices, thanks to the high number of political newcomers in LREM's ranks, although a number of defectors from both the Socialists and the Republicans will also be wearing its colours.