The robbery happened at 2:13 p.m. on August 23rd at 2101 Lehigh Avenue.
In surveillance video released Thursday by investigators, the woman is seen approaching the counter armed with a handgun.
The employee opens the cash register and hands over $160 in cash along with a pack of cigarettes.
The woman fled in a newer model white or gray SUV east on Allegheny Avenue.
The suspect is described as a black woman, 45 to 50 years old, 220 pounds, standing 5'7" tall, wearing a multi-color shirt.
Anyone with information is asked to contact Philadelphia Police at 215.686.TIPS (8477), text a tip to PPD TIP (773847) or through phillypolice.com.