While many suggested it was the result of voting fatigue, to some it's a dent in Macron's apparent success, (his effective share of the country's voter based was 15 per cent, given the low turnout) and one which could point to some of the problems that lie ahead for him as he starts to roll out his agenda.
"One year ago no one would have imagined such a political renewal", Prime Minister Edouard Philippe said in a statement.
Moreover, the scale of LREM's win means Macron will enjoy an absolute majority even without the support of alliance partner Francois Bayrou and Modem, lending him a freer hand for reforms and room for a government reshuffle should he chose.
The turnout in France's parliamentary election is trending low, with just over 35 percent of eligible voters casting ballots by late afternoon.
The vote comes just a month after the 39-year-old former banker became the youngest head of state in modern French history, promising to clean up French politics and revive the euro zone's second-biggest economy.
"People are exhausted of always seeing the same faces", said Natacha Dumay, a 59-year-old teacher voting in the northeastern Paris suburb of Pantin where Socialist former justice minister Elisabeth Guigou was voted out a week ago.
A statement from the Ministry of the Royal Household, Protocol and Chancellery said that Macron's visit to Morocco one month after his election at the Élysée, "reflects the depth of the bilateral relations that are based on a strong partnership and in favor of the common will consolidate the multidimensional links between the two countries".
Pollsters project that Macron's party and its allies won a clear majority in the National Assembly, the powerful lower house.
Commentators have warned that such an outcome would send shockwaves through the more established political order with their unity and even their survival at stake.
Polls suggest En Marche!, the fledgling party he founded only past year, may win up to 450 of the 577 seats in the national assembly, upsetting the established parties' grip on power. Others may see a future firmly in the opposition.
The conservative Republicans and its allies are set to form the largest opposition block with 97 to 133 seats.
Key battles on Sunday include far-right leader Le Pen's attempt to win her first parliamentary seat in the northeastern former coal mining town of Henin-Beaumont.
Le Pen's FN were only expected to win four to eight seats but she was elected an MP.
In the French mainland, 67,000 polling stations are set to close at 20:00 local time (1800 GMT) on Sunday in big cities and at 19:00 local time (1700 GMT) on the same day in other places. At that time, opinion polls will give an estimate of the outcome and official results will start trickling in.