Lazare Ponticelli, who came originally from Italy, had lied about his age so he could join the French Foreign Legion in 1914, aged 16.
Lazare Ponticelli's coffin was taken ceremoniously covered in the French flag, into the church at Les Invalides, which is the military hospice where Napoleon is buried.
France held a minute's silence, and flags were flown at half-mast on public buildings.
Former French President Jacques Chirac and current Prime Minister Francois Fillon were also in attendance at the memorial ceremony.
