Hundreds of thousands of people have signed a petition calling for Transport for London to reverse its decision to strip Uber’s licence.
More than 400,000 names have been added to the petition on Change.org after TfL said the firm would not have its licence renewed.
The regulator said the ride-hailing app firm was not “fit and proper” to hold a London private hire operator licence.
Uber says it will appeal against the decision.
The petition says: “If this decision stands, it will put more than 40,000 licensed drivers out of work and deprive millions of Londoners of a convenient and affordable form of transport.”
TfL said it had taken the decision on the grounds of “public safety and security implications”.
Its concerns include Uber’s approach to carrying out background checks on drivers and reporting serious criminal offences.
Uber claimed the move “would show the world that, far from being open, London is closed to innovative companies”.
Its licence is due to expire on 30 September.
Uber has 21 days to appeal against TfL’s decision and can continue to operate while any appeals are ongoing.
Some 3.5 million passengers and 40,000 drivers use the Uber app in London.