Police were called at about 8.50am on Thursday, 12 May to reports of a collision involving a moped and a pedestrian on Kennington Lane at the junction with Kennington Road, SE11.
Officers and the London Ambulance Service attended. The 82-year-old pedestrian was taken to a south London hospital with a serious head injury.
Despite the efforts of medical staff, the man died in hospital on Sunday, 15 May. His family has been informed.
The rider stopped at the scene and has spoken with police. There has been no arrest.
Detectives from the Roads and Transport Policing Command are investigating.
Enquiries continue to establish the circumstances of the collision.
Officers from the Serious Collision Investigation Unit based at Catford would like to speak with any witnesses who are yet to speak with police or anyone with dashcam footage. They are asked to call 020 8285 1574.