A bronze Renault Scenic and a blue Volkswagen Golf collided at 4.34pm on Saturday.
The Scenic driver, a man in his 40s, was taken to Southampton General Hospital with serious injuries.
The Golf driver, a 54-year-old woman, was pronounced dead at the scene. Her next of kin have been informed and are being supported by specialist officers.
Anyone who saw what happened, or who has dash-cam footage showing the collision or the moments beforehand, should call 101 quoting reference number 44210456392.