Kardashian’s bodyguard was handcuffed while men in police uniforms and armed with handguns robbed her, according to France Info TV.
A spokesperson said there were two assailants, although other reports said five.
"She is badly shaken but physically unharmed," the spokesperson said, shortly after her husband, rap superstar Kanye West, abruptly cut short a headlining festival set in New York.
An hour into his set, West said mid-song, "I'm sorry, show's over," and quickly left.
Kardashian, 35, who has two children with West, has been a fixture of US celebrity news for more than a decade, her career having been launched by a leaked sex tape followed by her family's reality TV show.
Kardashian has been in Paris for several days for fashion week and had attended the Baleciaga show before the robbery.
Last week was approached by Vitalii Sediuk, a famous accoster of stars, who was caught on video attempting to kiss her behind in an apparent social commentary.
Her security team stepped in, winning praise from Kardashian.