It happened at 10:20 a.m. at the Citizens Bank branch in the 2500 block of Welsh Road.
Police and the FBI say the man entered the bank, claimed to have a gun and demanded money.
He fled with an undisclosed amount of cash on a dark-colored motorcycle driven by a second suspect. The bike had a front storage bag and a broken turn signal hanging from the handlebars.
Police are looking for a white male, 25-30 years old, 5'2"-5'4" tall with a thin build.
He was wearing a black long-sleeve v-neck t-shirt with a white t-shirt underneath, blue jeans, sunglasses, and a red Phillies baseball cap.
He is considered armed and dangerous.
Anyone with information about this robbery or this subject is urged to call the FBI at 215-418-4000 or the Philadelphia Police Department.
There may be a reward for information leading to this subject's capture. Tipsters can remain anonymous.