The scale of the majority hands Macron, a pro-European Union neoliberal politician who served as economy minister under former President Francois Hollande, a strong platform to push through his agenda of market liberalization to benefit investors in the euro zone's second-biggest economy.
The far-right leader said that her party would oppose Macron's pro-Europe and pro-immigration stances and "fight with all necessary means the harmful projects of the government".
He said the Socialist party needs to change its ideas and its organization and that a "collective leadership" will replace him. Altmaier added: "Good for Europe and for Germany!". At the end of the afternoon, turnout stood at only 35 percent - below last week's record low.
Based on partial vote count made by Kantar Sofres-onepoint pollster, the LREM alone won 315 seats, more than 289 seats needed for a majority in the 577-member National Assembly, Xinhua news agency reported.
The far-right National Front (FN) improved its performance after snatching 6 seats compared to two now, while the outgoing ruling the Socialist Party, lost its lead with only 32 seats.
This is well down from 46.42 percent seen in the 2012 election and 40.75 percent in the first round of voting in these legislative elections on June 11.
He said French voters had "in their vast majority preferred hope to anger, optimism to pessimism, confidence to withdrawal".
Commenting on the low turnout, Le Pen said it could undermine the legitimacy of the newly elected parliament.
The hard-left France Unbowed also struggled to maintain the momentum it had during the presidential election.
The voting system punishes parties outside the mainstream, or with no mainstream allies, like Le Pen's National Front. Experts partly blamed voter fatigue following the May election of Mr Macron, plus voter disappointment with politics.
The three projections predicted the conservative Republicans and their allies would form the largest opposition bloc with 107-133 seats, while the Socialist Party - in power for the last five years - and its partners would secure 30-49 seats, their lowest ever.