Having an absolute majority in the National Assembly, France's lower and more powerful house of parliament, will allow Macron to govern more at ease during his five-year term.
The National Front of far-right leader Marine Le Pen looked unlikely to convert her strong showing in the presidential election into a large number of legislative seats.
Candidates in the runoff of French parliamentary elections are hitting the campaign trail to try to lure voters to cast ballots next weekend after a record abstention rate in the first round and a likely sweep by President Emmanuel Macron's new party.
A swath of senior Socialists, including former government ministers, lost their seats in the first round.
The right-wing Republican party, which only at the start of this year had seemed on course to win the Presidency under Francois Fillon, will be nearly certainly be the main opposition, with between 70 and 110 seats according to Ipsos projections.
But turnout was sharply down, at 48.7 per cent compared with 57.2 per cent in the first round in 2012, which analysts said reflected a sense of resignation among Macron's opponents.
The spread, the premium investors are willing to pay for German bonds, indicates investor perceptions of France-specific political risk.
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.
"Despite the abstention, the message of the French has no ambiguity: For the third consecutive time, millions of you confirmed your attachment to the president of the republic's project to renew, unite and win back". Those who did gave Macron's the Republic on the Move party 28 percent of the vote - more than 12 points ahead of the closest rival, the.
Reformist Mr Macron has pledged to strengthen European Union ties, stabilise public finances, and loosen strictures on business.
Macron had thrown Les Republicains off balance by nominating two high-profile party members, Edouard Philippe and Bruno Le Maire, as his prime minister and economy minister.
If no candidate manages to achieve that target then all candidates who win at least 12.5% of registered voters will go into the second round, where the victor will advance to parliament.
Socialist Party leader Jean Christophe Cambadelis said the record-low turnout was a "sign of enormous democratic fatigue". One of those seats may be her own: Ms Le Pen came out on top with 45-47% of the vote in the northern French constituency centred on Hénin-Beaumont, a former mining town, giving her a strong chance of securing the seat at the run-off.
"Chancellor Merkel: My honest congratulations to Emmanuel Macron for the great success of his party in the first round".
Parties on the extreme right and left seemed to be faring poorly, gaining far fewer votes nationwide than they had in the first round of the presidential election, on April 23.
François Baroin, who ran the campaign of conservative party The Republicans, echoed these sentiments, saying political power should not be concentrated in the hands of one party and urging supporters to turn out on 18 June for the decisive second round.