In their only televised debate before voters have their say in Sunday's run-off, Mr Macron sought to portray Ms Le Pen as fundamentally untrustworthy, accusing her of dishonesty in her election promises.
Ms Le Pen, whom Mr Macron beat in the last presidential election five years ago, is doing better in polls this time although she still trails the incumbent president.
Ms Le Pen an anti-immigration nationalist who has gained ground this year by tapping anger over inflation, has significantly narrowed the gap in public support compared to 2017, when she lost with 34% of the vote to Mr Macron's 66%.
Both candidates had prepared carefully for Wednesday's debate. But Ms Le Pen made an inauspicious start: Having been picked to speak first, she started off before the debate's opening jingle had finished playing. Inaudible because of the music, she had to stop and start again.
Once the jousting began, Mr Macron quickly put Ms Le Pen on the defensive. He zeroed in on her voting record as a lawmaker and questioned her grasp of economic figures.
Millions of voters remain undecided and the debate, which was close to three hours, soon burst into life as the candidates clashed over the EU, cost of living crisis, the environment and the banning of the hijab, which sparked a constitutional debate.
Ms Le Pen said: “I am in favour of banning the hijab in public. I was extremely clear about that, I think the hijab is a uniform imposed by Islamists.
"Many of the women who wear it have no choice, even if they dare not say so, because those who do not wear it reveal how they are insulted, ostracised, and accused of being impure. That is what I believe.”
She added: “This situation is intolerable in our country. We need to liberate these women from Islamists.
"That is why I believe that we must ban the hijab in public.”Responding however, Mr Macron said that such a move with lead to a direct confrontation with France’s constitution.
He said: “This issue is about religion. The hijab or the scarf is a religious sign.
“I am in favour of the 1905 law on secularism in one republic. Secularism is not about fighting a religion.
"I will not ban any religious sign in public, whether the scarf or the kippah.
“If you go down that road you’ll have to ban all religious signs in public. I have read the French constitution, I am sorry to have to remind you about it, the laws that you will enact, if you were elected, will have to respect a constitution and our basic law enshrines secularism, which is all about freedom."
He added: “State institutions have an obligation of absolute neutrality, but in the public realm, you will create civil war.”
Ms Le Pen hit back saying that Mr Macron had launched a serious accusation and he was assuming people would flout the law, however, Mr Macron responded saying that her policy would make France the first country in the world to ban religious signs in public.
The French leader was also particularly vocal in his criticism of a loan taken out by Ms Le Pen's party in 2014 from a Russian-Czech bank.
He said that debt meant that, if elected president, Ms Le Pen's hands would be tied when dealing with the Kremlin.
"You are speaking to your banker when you speak of Russia, that's the problem,"
"You made a choice which, obviously, acted as a constraint on your political position and does not make you independent on that issue. That is a fact," Mr Macron said.
Ms Le Pen bristled at Ms Macron's suggestion that she is beholden to Russia. She described herself as "totally free." She said her party is repaying the loan and called him "dishonest" for raising the issue.
Both candidates clashed on the European Union with Marine Le Pen has changed her policy from leaving the EU to seeking change from within it arguing that the EU was failing to defend the interests of France and that and she would stop negotiating trade deals that "hurt French producers and farmers"– in response Mr Macron argued that her idea of a "Europe of nations" would spell the end of the EU and accused her of “selling a lie".
Le Pen also said that she would tackle the cost of living crisis stating "I will permanently cut VAT on energy. I will also cut taxes, no income tax for under-30s."
Mr Macron hit back saying his solution was to impose a cap on prices was "twice as effective as dropping sales tax".
Mr Macron, a pro-European centrist, emerged ahead from the April 10 first round and is leading in opinion polls, even after the debate.
Both candidates need to broaden support before Sunday's vote. Many French, especially on the left, say they still do not know whether they will even go to the polls.
A poll of voters from French broadcaster BFMTV and newspaper L'Express suggested Mr Macron had come out the winner, with the poll from pollsters Elabe, suggesting that 59% of viewers were more convinced by Mr Macron.
The poll found sitting president came out on top as the most presidential, 53% to 29% - but 50% of viewers also said he had come across as arrogant. Ms Le Pen was deemed to be more in tune with normal people (37% to Macron's 34%), but 50% of voters also found her "worrying".