The man, aged in his 20s, is in a critical condition after the collision in Kenworthy Road, Homerton, around 7.40pm on Sunday.
He was injured after being hit by a car which then struck another vehicle.
The driver of the car, a 24-year-old woman, has been arrested of causing GBH by dangerous driving. She remains in custody.
The cyclist was rushed to hospital for treatment, and his next-of-kin have been informed.
On Monday morning, police issued an appeal for witnesses and dashcam footage to the incident.
Officers said road closures which had been in place in the area have since been lifted, while their probe continues.
Anyone with information that could assist the investigation, or footage, is being asked to call 0208 597 4874. You can also provide information via Twitter @MetCC, quoting CAD7039/10Sep.