Police say she was approached by a man with a knife at New Barnsley Park at about 21:00 BST on Friday.
The attacker damaged the front window of the car, forced her out of it and then drove off.
The car was later found abandoned at La Salle Drive.
The woman was not hurt, but was left shocked.
Detectives in west Belfast have appealed for anyone with information about the incident to contact them on the non-emergency 101 number.