The 24-year-old suspect smashed into the store around 2am on the high-end Rue Saint-Honoré, a police source said.
He grabbed as many as 30 luxury handbags and other items before attempting to flee in the car.
The man then failed to stop when a police patrol gave chase after spotting him near the central Paris Opéra.
He abandoned the car on Place de la Concorde at the end of the Champs-Elysées, the police source said, before plunging into the nearby river Seine.
But river police quickly fished him out and placed him under arrest.
A source familiar with the case said that the “entirety” of the stolen items had been found.
A second source told AFP that “around 30” handbags – which Valentino lists on its website at between €1,000 and €3,000 – were found in his car.
The suspect now faces an investigation for charges including aggravated robbery and refusal to comply with police, Paris prosecutors said.