Police released surveillance video on Friday of the incident that happened shortly after 11:00 p.m. on April 27th at the Dunkin' Donuts store at 330 Oregon Avenue.
Investigators say an unknown man entered the store and placed an order.
As the employee turned around, the suspect pulled a knife and demanded $50.
However, the situation was turned on its head when the employee grabbed a 15-inch knife in self defense.
The would-be bandit fled the store and got into a nearby SEPTA bus, travelling west on Oregon Avenue.
The suspect is described as a white male, 30 to 35 years old standing six feet tall with a thin build. He was wearing a grey hooded sweatshirt, blue jeans and white sneakers.
Anyone with information is asked to contact Philadelphia Police at 215.686.TIPS (8477) or through phillypolice.com.