France's leader was set for a parliamentary majority in the first round of the election but rivals warned him about the low turnout.
French voters have put President Emmanuel Macron's party on course for a crushing parliamentary majority, though a record low turnout in the first round of voting raised concerns Monday over the strength of his future mandate.
The vote delivered a further crushing blow to the Socialist and conservative parties that had alternated in power for decades until Macron's election in May blew apart the left-right divide
Official final results showed his year-old REM (Republic on the Move) and allies MoDem winning 32.32 percent, ahead of the right-wing Republicans and its allies on 21.56 percent and the far-right National Front (FN) of Marine Le Pen on 13.20 percent.
The election result would give France's youngest leader since Napoleon a powerful mandate to make good on campaign pledges to revive France's fortunes by cleaning up politics and easing regulations that investors say hobble the euro zone's second-biggest economy.
"France is back," Prime Minister Edouard Philippe declared triumphantly, calling the result a vote for the president's "confidence, will and daring".
But government spokesman Christophe Castaner admitted the 49 percent turnout - the lowest for six decades in such a vote - was "a failure of this election" and that Macron's team would need to reach out to those who stayed away.
Merkel congratulates Macron
German Chancellor Angela Merkel called the victory of French President Emmanuel Macron's party in the first round of parliamentary elections a "strong vote for reforms."
France is Germany's second-biggest trading partner and the strong support for pro-European centrist reformer Macron has sparked hopes that Berlin and Paris will spearhead a broad-based economic revival in Europe and a push for more integration in the eurozone.
"Chancellor Merkel: My heartfelt congratulations to @EmmanuelMacron to the great success of his party in the first election round. Strong vote for reforms," the government tweeted.
Merkel and Macron agreed last month to draw up a roadmap to deeper EU integration and suggested the bloc's treaties may change to facilitate even more ambitious reform.
Poland warned on Monday against rising protectionism in Europe following the victory of Macron's party in the first round of parliamentary elections.
Macron has called for a "protection agenda" for the EU that includes a "Buy European Act" and regulations to prevent strategic companies from falling into non-European hands.
Konrad Szymanski, Poland's deputy foreign minister in charge of European affairs, told reporters in Berlin that other EU governments might adopt a more protectionist stance to support Macron.
The future development of the EU's single market is causing the biggest concerns for us," Szymanski said in reference to Macron's agenda.