Macron finally ended speculation about his intentions by announcing his candidacy for his "En Marche" ("On the Move") centrist party from a training centre in a gritty suburb northeast of Paris.
Never elected and "neither of the left or the right" in his own words, the pro-business and technology-savvy former investment banker is hoping to shake up a race between older, more familiar figures.
"I'm ready, that's why I am candidate for the French presidency," he said, promising a "democratic revolution" that would restore France's optimism and self-confidence.
The far-right National Front under leader Marine Le Pen, who announced her election campaign logo Wednesday, is seeking to capitalise on a surge in nationalism and anti-globalisation.
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Macron, who quit the beleaguered Socialist government in August to focus on his own political movement, is expected to steal centrist voters from the Republicans and the left.
A poll yesterday showed him as one of France's most "presidential" figures behind the favourite Alain Juppe, a 71-year-old former prime minister from the Republicans who has one of the longest CVs in French politics.
"I believe that the French people won't put their destiny in the hands of someone with no experience," former prime minister and another Republicans candidate, Francois Fillon, said today.
Leftist Socialist rival Arnaud Montebourg dismissed Macron as the "media's candidate who has been on 75 magazine front pages despite never having proposed anything."
But Macron believes his youth and inexperience are assets in a country weary of a political class blamed for years of tepid growth, high unemployment and mounting government debt.