It happened Sunday morning on East Clayton and Green avenues.
In a preliminary report, authorities say the male walked up to the woman's car with a knife and demanded her to get out.
The victim complied and the suspect took her car, speeding down Green Street toward Academy Street. The woman was not injured.
Police are still searching for the suspect and the car.
The vehicle is described as a 1999 Gold Chevy Caviler.
The suspect is described as a man in his 30s. He was wearing sunglasses and a red bandana at the time of the incident.
Anyone with information is asked to Clayton Police.