Police were called to the scene by the London Ambulance Service at 10.43am, to reports of a collision between a car and a female pedestrian on Bessborough Road at the junction with Whitmore Road.
The woman, who was in her 70s, was pronounced dead at the scene at 11:38am.
London's Air Ambulance also attended the incident.
Next of kin are being informed and a post-mortem examination will be carried out in due course.
The car stopped at the scene of the collision and detectives from the Met's Serious Collision Investigation Unit are now investigating.
Witnesses are urged to contact the witness appeal line on 020 8991 9555 or via Twitter @MetCC.
No arrests have been made and enquiries into the incident continue.
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