Transport for London has said it won't be renewing Uber's operating licence in London when its current one expires next week.
While the ride-hailing app has 21 days to appeal, and can continue operating throughout the appeals process, the news from TfL has stirred up a variety of reactions.
One MP applauded what he called the bravery of TfL's decision.
"This is a courageous decision by the Mayor and Transport for London, finally drawing a line in the sand to make it clear that no company, however big and powerful, will be allowed to flout our laws and regulations or jeopardise Londoner's safety without facing serious consequences," said Wes Streeting, MP for Ilford North and chair of the All Party Parliamentary Group on Taxis.
"Uber has not shown itself to be a fit and proper operator. Its business model is based on saturating London's taxi and private hire market to drive its competition off the road. That's why major cities across North America and Europe have already banned Uber from operating on their roads.
"Competition and innovation is welcome and encouraged, but everyone must abide by the rules. If Uber want to operate on the streets of London again, they should clean up their act by putting passenger safety first, paying their drivers fairly by recognising their rights as employees and adhering to the same rules as everyone else.
Sadiq Khan gave fair warning when he stood for election that he would take action if Uber, or any other operator, failed to play by the rules. Today's decision shows that the Mayor keeps his word and is prepared to stand up to powerful vested interests to keep Londoners safe.
However, others say the decision is "damaging".
London Assembly member Andrew Boff said: "This is a hugely damaging decision by Sadiq Khan that will effectively put 40,000 people out of work at the click of a finger.
The mayor consistently tells us London is open but in shutting down the operations of an innovative market leader like Uber he has caused immense reputational damage to our city as a global business hub.
"With 3.5m registered users - almost half the city's adult population - Uber has shown to be providing a hugely beneficial service to Londoners."
Boff added: "Sadiq Khan has ignored their needs and instead believed the smears and propaganda propagated by Uber's rivals.
"Yes there are elements of the industry that need tweaking, yes there needs to be a reduction of bureaucracy for black cab drivers, but snuffing out the competition at the expense of thousands of employees and millions of customers is not the solution."
Mark Littlewood, director general at the Institute of Economic Affairs, said the decision "strikes a huge blow to competition and innovation within London’s transport market".
"If this ruling is upheld, it will ruin flexible working opportunities for the 40,000 city drivers who use the app – many for their livelihood, and many to top up low wages," he said.
"The ruling also inconveniences the 3.5m Londoners who regularly use the service, and reasserts the dominance of the city’s taxi cartel, which only the wealthiest residents can afford to use with any sense of frequency.
"Banning Uber, and clamping down on the gig economy more generally, is a restriction upon freedom of choice, both for Uber's drivers and passengers. In doing so, Transport for London has privileged the views of a powerful minority who wish to restrict consumer choice over the will of millions of ordinary Londoners.
Today’s decision is an assault on drivers and customers alike, and a victory for protectionism.
Sam Dumitriu, research economist at the Adam Smith Institute, said: "TfL's decision to revoke Uber's license is a disaster for Londoners. They are choosing to punish the 3.5 million Londoners who regularly use Uber just because it's cheaper, it's safer, and it's quicker. This decision jeopardises the livelihoods of 40,000 drivers who choose to use the app because it gives them valuable flexibility.
"The only people that will benefit are the Black Cab lobby who have crushed a competitor through cronyism, rather than providing a better service. Londoners will face higher prices, longer wait times and will no longer benefit from a safe service where every journey is logged and tracked by GPS.
Sadiq Khan likes to claim that London is open, but this decision sends a powerful message that London is completely closed to innovation, competition and business.