Uber is mounting a legal challenge to the decision by Transport for London not to renew its private hire licence when it expires at the end of this month.
The ride-hailing giant has 3.5 customers and 40,000 drivers in the city.
Its licence has been refused because TfL believes it shows a lack corporate responsibility, which could have implications for public safety and security.
These include its approach to reporting serious criminal offences and how medical certificates and DBS checks are obtained.
In a statement Uber said: “Transport for London and the mayor have caved in to a small number of people who want to restrict consumer choice.”
It added: “Uber operates in more than 600 cities around the world, including more than 40 towns and cities here in the UK. This ban would show the world that, far from being open, London is closed to innovative companies who bring choice to consumers.”