LONDON—London’s top transport authority stripped Uber Technologies Inc. of its private-car hire license in the city, threatening to shut the company out of one of its biggest markets.

The surprise decision presents another obstacle for the company as it tries to pare heavy losses and right itself amid a series of scandals, probes and board infighting. The authority, Transport for London, cited “a lack of corporate responsibility” that it said could undermine public safety and security, and said it won’t issue Uber a new license...