She was on or near a pedestrian crossing close to the junction of the B2223 Dominion Road with Southdown View Road when she was hit at 6.50pm on July 31.
She suffered serious injuries, including multiple fractures and was flown to Southampton General Hospital, where she died on Saturday night.
Police are appealing for witnesses to the collision and in particular, drivers of other cars who were in the area at the time who may have seen the silver Ford Focus estate that was involved. Please email [email protected] or call 101 quoting Operation Foxcote.
A 51-year-old man from Hurstpierpoint was arrested on suspicion of dangerous driving and has been bailed until October 23.