Police were called to the crash at the junction of Garrads Road and Tooting Bec Road in Lambeth soon before 1pm on December 12.
Paramedics treated the girl at the scene and rushed her to hospital, where she died on Monday (January 5).
A 54-year-old man was arrested at the scene on suspicion of causing injury by dangerous driving and on suspicion of driving under the influence.
He has since been bailed while enquiries continue and police appeal for further information from the public.
Detective Chief Superintendent Emma Bond, who leads policing in the local area, said: “The victim’s family are going through unimaginable pain, and our thoughts remain with them at this time.
“We have spoken to a number of people who witnessed the collision, but we would like to encourage anyone else who was in the area at the time of the incident to come forward with any information that may assist the investigation.”
Anyone with information is urged to call 101, quoting reference 3570/12DEC25.
