"TfL has concluded that Uber London Limited is not fit and proper to hold a private hire operator licence".
More than 515,000 people entered their names by 1200 GMT on Saturday in support of the USA -based company, which urged users to sign in order to keep its cars on London roads.
Responding to the petition, Fred Jones, Uber's United Kingdom head of cities, told the BBC: "I think people realise that this decision by the mayor and Transport for London is actually because they have caved to pressure from a small number of individuals and groups that want to protect the status quo and reduce consumer choice and competition from London".
In a strongly-worded statement, Transport for London said Uber was "not fit and proper" to operate in the capital on the grounds of "public safety and security implications", including the company's approach to reporting serious criminal offences.
A British government minister has criticised the London authorities for deciding to strip Uber of its taxi licence, a major setback to the USA technology firm that has become a big player in the city's transport system.
"Mr. Khan has just been told that he will be given a platform at the Labor Party conference and TfL's decision is sure to earn him a rousting endorsement from an audience of activists and trade unionists". The transport app will have 21 days to appeal the decision.
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Although it is for British authorities to decide, Ross insisted that "Uber is a wonderful invention", and the problem is "London cabbies have been slow in adjusting to the new system".
"TfL isn't anti-private hire vehicle operators, what TfL is against is companies not playing by the rules so customers, members of staff and others should be angry at Uber for not playing by the rules, rather than TfL who are doing their job by making sure companies are playing by the rules".
Regulators said it denied the license because Uber's "approach and conduct demonstrate a lack of corporate responsibility".
Those millions of residents who use the service, which is in most instances considerably cheaper than hiring one of London's famous black cabs, are not happy about the decision. "Pls work w/us to make things right", Khosrowshahi wrote.
The Uber service has become the darling of most Londoners, but in a city filled with well-known black cabs and minicab firms, there are plenty of alternatives out there.
Post-Kalanick woesThe loss of the San Francisco-based start-up's licence comes after a tumultuous few months that led to former CEO and co-founder Travis Kalanick being forced out.
The online ride-hailing pioneer said it still operates in 96 European cities but has largely withdrawn its UberPOP service that relied on drivers without commercial licenses after court rulings against it in many jurisdictions going back years.