The Pulaski County Sheriff's Office (PCSO) says Robert Gates, 19, pointed a gun at the store clerk, then took cash and cigarettes from the Valero at 14401 Arch Street Pike.
It happened shortly after 2:30.
Gates was reported to have worn a hooded sweatshirt with the hood pulled tight around his face showing only his eyes, during the holdup.
He was pulled over in a traffic stop a short time later at Scott Hamilton Drive and 81st Street and taken into custody.
The incident report notes that Gates took an undetermined amount of cash, 24 packs of Newport cigarettes and 21 packs of Marlboro Light cigarettes from the business.
The PCSO says Gates also confessed to robbing the same store last week.