At approximately 12:45pm on Thursday, 18 March, an unidentified vehicle collided with an electric scooter on Thornton Heath High Street in Croydon, near the junction with Grange Road and Whitehorse Lane.
Officers and the London Ambulance Service (LAS) attended the scene.
The man, who was riding the e-scooter, was taken to a south London hospital by LAS where he continues to receive treatment for potentially life-changing injuries.
The driver did not stop at the scene. It is believed that the vehicle was dark coloured; no further details are known at this stage.
Police are keen to speak with anyone who witnessed the collision or may have captured it on dashcam footage.
Anyone with information is asked to call police on 101 or tweet @MetCC quoting CAD 3233/18MAR21.