It happened in a car park of Millennium Way in west Belfast shortly before 8 am on Friday morning as the woman arrived for work at a call centre.
A 22-year-old has been arrested on suspicion of hijacking a number of other offences after he was detained in a suspected stolen car on the Whiterock Road.
It was reported that a man threatened the young woman in a car park before stealing her car keys and making off in her Peugeot 107 car.
The car was reported driving dangerously on the Whiterock Road a short time later.
Members of the public were able to restrain the suspect until police arrived and arrested him.
He remains in custody at this time.
Detective Inspector Nigel Snoddy said: “I am appealing for anyone who witnessed the incident or anyone who has any information that can assist with the investigation to contact detectives at Musgrave Police Station on 101, quoting reference number 201 of 23/09/16.
” Or if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”