Officers were called at approximately 4.17am on Friday, 10 December, to the collision in Streatham High Road, SW16.
The rider of the motorcycle, a 20-year-old man, was taken to a south London hospital. His injuries have been assessed as life-threatening.
The man’s family have been informed.
There has been no arrest. Enquiries continue to establish the circumstances.
Officers from the Serious Collision Investigation Unit based at Catford are investigating this matter. Any witnesses who are yet to speak with police or anyone with dashcam footage that may assist are