Macron announced that volunteers aged 18 and 19 would start serving next year in a 10-month new military service program.
"A new national service is set to be gradually established, starting from next summer," Macron said in a speech on Thursday at the Varces military base, which is in the French Alps.
Young volunteers would serve in France's mainland and overseas territories only, not in France's military operations abroad, Macron said.
Earlier in 2025, Macron announced his intention to provide French youth with a new option to voluntarily serve in the military.
Conscription, which France ended in 1996, is not being considered.
He said France was seeking to boost its defences as Russia's war in Ukraine puts the European continent at "great risk".
"The day that you send a signal of weakness to Russia - which for 10 years has made a strategic choice to become an imperial power again, that's to say advance wherever we are weak - well, it will continue to advance," he told radio RTL on Tuesday.
Macron has announced 6.5 billion euros ($A11.5 billion) in extra military spending in the next two years.
He said France would aim to spend 64 billion euros in annual defence spending in 2027, the last year of his second term.
France's military comprises about 200,000 active personnel and more than 40,000 reservists, making it the second largest in the European Union, just behind Poland.
France wants to increase the number of reservists to 100,000 by 2030.
France's new army chief of staff, General Fabien Mandon, last week sent a warning about the nation's need to get prepared to "lose its children" in the event of a potential conflict with Russia - words that prompted an outcry across the political spectrum.
"Unfortunately, Russia today, based on the information I have access to, is preparing for a confrontation with our countries by 2030. It is organising itself for this, it is preparing for this, and it is convinced that its existential enemy is NATO," he said.
Macron has made clear the national military service volunteers would not be sent to the front line.
"We must, in any case, immediately dispel any confusion that we are going to send our young people to Ukraine," Macron said on Tuesday.
"That's not at all what this is about."
France is not the only European nation bolstering its military capabilities.
Germany is redoubling its efforts to attract more recruits, notably via a yet-to-be-approved voluntary military service, while Belgium is encouraging 17-year-olds to sign up in 2026.
Poland has started rolling out a new voluntary military training program and aims to train 100,000 volunteers a year from 2027.
Ten EU countries have compulsory military service: Austria, Cyprus, Croatia, Denmark, Estonia, Finland, Greece, Latvia, Lithuania, and Sweden.
