Police found the victim on the 2200 block of Fernon Street around 12:30 a.m. Thursday.
Medics said the victim had a gunshot wound to his head. He was pronounced dead at the scene.
But there were no shell casings at the scene, and neighbors did not hear gunshots.
Police did find blood and some dollar bills nearby the victim.
"It's fresh, it's close to the victim, so it's possible that this is related to a robbery," Philadelphia Police Chief Inspector Scott Small said.
Investigators are not ruling out the possibility the cash could be from a drug deal or another type of transaction.
The victim had no identification on him, Small said.