The crash happened at about 4.30pm on Becquet Road, above Fermain.
Guernsey Police are still trying to determine exactly what happened, but it appears that the car lost control down the steep road and clipped the granite entrance to the footpath, which possibly flipped the car onto its side.
The vehicle then continued down the narrow path several metres, before rolling off the footpath and onto its roof.
Guernsey Fire and Rescue were called at 4.34pm and were on the scene 10 minutes later.
Incident Commander Matt Roger said when they arrived the car was on its roof, wedged against two trees above a steep drop down to Le Becquet Point.
The female driver and her Jack Russell dog were trapped in the inverted vehicle and the emergency services could communicate only through a car window.
