The pedestrian, who was 22, was injured on the A12 at around 8.50pm on Wednesday, 19 June.
She was taken by air ambulance to a hospital in south London but she passed away on the afternoon of Friday, 21 June.
The driver of the car stopped at the scene and was not arrested but investigators are continuing to carry out enquiries.
Detective Sergeant Jose Qureshi said: “Officers from the Serious Collision Investigation Unit are working to establish the full circumstances surrounding
this incident.
“I am asking for anyone who witnessed the incident, or who has dash cam footage, to make contact with us as soon as possible.”
Anyone with information asked to contact the SCIU on 020 8597 4874. Alternatively tweet @MetCC or call 101 ref CAD 7861/19Jun.
Tags: Romford, Havering, A12, Gallows Corner