The robbery happened Wednesday morning at a TCF Bank branch near 61st and Archer. The bank is inside a Jewel grocery store.
The robber, described as a white man between 20 and 25 with green eyes and overgrown shaggy facial hair, was armed with a black handgun and wearing a gray hooded sweatshirt under a black jacket, according to police and surveillance camera photos.
The suspect got away with an undisclosed amount of cash.
Nobody was hurt, according to Chicago police.
The FBI says it is the 35th confirmed bank robbery in the Chicago area so far this year.
The Sun-Times Media Wire contributed to this report.