The theft took place during the day in the Place Vendome area, the site of another high-profile robbery last year.
Video footage on Twitter — which Paris police confirmed was authentic — showed one robber with what appeared to be an automatic weapon outside the Chanel shop on Rue de la Paix.
Seconds later, three other robbers — dressed in black and wearing helmets — stormed out of the boutique holding bags and the four sped off on two motorcycles.
“It all happened very quickly and unfortunately the first police officers who arrived were on bicycles,” a bystander who had filmed the event told Reuters. He declined to be identified.
Chanel said no one was injured and it was working with police. The retailer did not disclose the value of the stolen goods. Police said they have no information on the identity of the thieves.
The privately owned French luxury fashion house's Rue de la Paix outlet is a temporary shop selling watches and jewellery, set up while the Place Vendome flagship boutique is undergoing a revamp.
Jewellery shops in Paris have suffered a spate of armed robberies in recent months.
In September, Paris police caught three suspected armed robbers after opening fire on their car as they made their getaway from a €10 million ($12m) jewellery heist at a Bulgari shop in Place Vendome.
In July, thieves made off with jewellery worth almost €2m from a Chaumet shop near the Champs-Elysees, although the stolen goods were later recovered and the suspects arrested.