Regulators Transport for London (TfL) stated that they have decided to remove the rid-hailing app's operating licence as they are aware of "a pattern of failures" made by the firm which put passengers' safety and security at risk, and concluded that this means that the company is "not fit and proper at this time".
Uber has been given 21 days to appeal the decision and they are allowed to operate until the process is complete.
Helen Chapman, director of licensing, regulation and charging at TfL, said: "As the regulator of private hire services in London we are required to make a decision today on whether Uber is fit and proper to hold a licence. Safety is our absolute top priority.
"While we recognise Uber has made improvements, it is unacceptable that Uber has allowed passengers to get into minicabs with drivers who are potentially unlicensed and uninsured.
"It is clearly concerning that these issues arose, but it is also concerning that we cannot be confident that similar issues won't happen again in future.
If they choose to appeal, Uber will have the opportunity to publicly demonstrate to a magistrate whether it has put in place sufficient measures to ensure potential safety risks to passengers are eliminated.
"If they do appeal, Uber can continue to operate and we will closely scrutinise the company to ensure the management has robust controls in place to ensure safety is not compromised during any changes to the app."
Uber has hailed the decisions as "extraordinary and wrong" and vowed to appeal.
The firm's regional general manager for northern and eastern Europe, Jamie Heywood, said: "TfL's decision not to renew Uber's licence in London is extraordinary and wrong, and we will appeal.
"We have fundamentally changed our business over the last two years and are setting the standard on safety. TfL found us to be a fit and proper operator just two months ago, and we continue to go above and beyond.
"On behalf of the 3.5 million riders and 45,000 licensed drivers who depend on Uber in London, we will continue to operate as normal and will do everything we can to work with TfL to resolve this situation."