Uber Technologies Inc. was slapped with a 400,000 euro ($459,000) fine by France’s privacy watchdog following a 2016 cyber attack that compromised the data of millions of customers and tens of thousands of drivers.

It’s the third European penalty over the same breach, France’s CNIL said, adding that it was publishing its decision due to “the very high number of people concerned and the need to make other operators aware.” The Paris-based watchdog accused Uber’s French unit, Uber France SAS, of failing to sufficiently protect the data of its users.

The company revealed in November last year that hackers had...