It happened around 2 a.m. Tuesday at the 7-Eleven store located at 1435 Cottman Avenue.
Police said the man entered the store and asked the clerk for an electronic cigarette.
After receiving the item, video shows him putting his hand in his jacket pocket to mimic a weapon.
Police said the suspect told the clerk, "Give me all of the money."
The man got away with approximately $250 from the register.
Anyone with information is asked to contact police.