Police say the woman got out of the vehicle and an unknown man jumped in and took the car.
The incident happened at Boucher Crescent in south Belfast at about 5.25 pm on Saturday.
Members of the public managed to stop the car but the man fled on foot.
A short time later a man in his 30s was arrested.
He was detained under the Theft Act and taken to the PACE custody suite at Musgrave PSNI station.
Police said two children were unharmed during the incident.