Amid delighted gasps from onlookers, the soldier, dressed in ceremonial uniform, dropped to his right knee and briefly spoke to his girlfriend before placing a ring on her left hand, a video posted on the land army's twitter handle showed.
"Everything is possible for our soldiers on the day of the #NationalHoliday. All our congratulations," a tweet by the army said.
The proposal took place as members of the armed forces prepared for the traditional July 14 military parade along the famed boulevard linking the Arc de Triomphe with Place de la Concorde.
The soldier's partner was allowed through a security cordon after the army learned of their comrade's intentions, a land army spokeswoman said.