The robbery took place around 12:40 p.m. at the bank on the 7300 block of Frankford Avenue in Mayfair.
Police say the male suspect entered the store and handed a teller a demand note.
After obtaining an undisclosed amount of cash, the suspect fled the bank on foot, heading south on Frankford Avenue.
The suspect is described as a white male in his 20s, approximately 5'10, thin build, with a beard and mustache and a heavily bandaged left hand. He was wearing a gray hooded sweatshirt, black jacket, and gray Philadelphia 76ers cap.
Police say the suspect is to be considered armed and dangerous.
Anyone with information should call the FBI at 215-418-4000 or the Philadelphia Police Department.
There is a reward for information leading to the suspect's capture.