The incident happened at 5:30 p.m. at the Metro PCS store located on the 1400 block of Point Breeze Avenue.
Police say the male suspect entered the store armed with a handgun and approached the counter.
He handed the clerk a black plastic bag and demanded cash.
The robber got away with an unknown amount of money from the register before fleeing towards Dickinson Street.
The suspect is described as a black male, 20-years-old, 6'1"-6'2" tall with broad shoulders. He was wearing sunglasses, a white hooded sweatshirt, gray sweatpants and white loafer shoes.
Anyone with information on this robbery should call South Detectives at 215-686-3013/3014.