The safes of three rooms at the hotel were broken into and jewellery and other valuables estimated at 40,000 euros ($53,000) were stolen, the hotel management reported on Friday evening.
Police blocked the roads on the Cap Ferrat peninsula but the thief or thieves escaped.
The theft comes after a string of jewel robberies in the nearby resort of Cannes, including a record $136 million (103 million euro) theft from an exhibition at the luxury Carlton hotel last weekend, one of the world's biggest jewellery heists.
Then on Wednesday two men armed with a grenade and a gun burst into a Cannes store selling luxury watches and made off with items worth one to 1.5 million euros.
Friday's small-size theft of jewels is the kind that happens frequently during the summer holidays in the French Mediterranean resorts, local police said.
Cannes was also hit with a wave of jewellery robberies during its annual film festival in May.