The new French president’s party is on course to win a large majority of seats – although far right Marine Le Pen has also won her first parliamentary seat.
Emmanuel Macron’s new centrist party has a clear lead over the traditional left and right parties, partial official results show.
The election was for the National Assembly, the lower house in French politics.
It follows the presidential election last month. Many candidates in En Marche! joined only after he won the presidency.
Le Pen, who came in second place to the pro-EU candidate for the presidency, celebrating winning her first seat. She said although Macon now has a majority in parliament, his ideas are a ‘minority’ and said the Front National will fight his reform plans.
With 57% of votes counted, the Interior Ministry said that Mr Macron’s Republic on the Move! party had won 41% of the vote, followed by the conservative Republicans with 23%.
The ministry said the far-right National Front was in third place with nearly 10% followed by the Socialists with 6.2%.
Turn-out was also thought to be down.
Pollsters project that Mr Macron’s party and its allies won a clear majority in the National Assembly, the powerful lower house.
Later, France’s conservative leader declared his party the main opposition.
Republican leader Francois Baroin wished President Macron luck because he said he wants France to succeed.
He said politicians in his conservative party are going to have a strong enough bloc in the lower house of parliament to be able to voice their views.