It happened around 11:30 p.m. along the 2200 block of S. 6th Street near W. Moyamensing Avenue.
Investigators said a 24-year-old man was smoking a cigarette in front of his house when a 30-year-old man on a bicycle approached him with a gun and announced a robbery.
Police said the 24-year-old pulled out his own handgun and fired one shot as the other man was stepping off of the bicycle.
Arriving officers found the bicyclist on the sidewalk with a single gunshot wound to the head.
The male suspect lost consciousness while medics were rushing him to Jefferson University Hospital; he was later pronounced dead around 2 a.m. Thursday, according to police.
Investigators said the bicyclist also fired his weapon during the shooting.
"According to the 24-year-old who fired the shot, the perpetrator, after being shot in the head, pulled his gun and fired one or two shots, but did not strike the 24-year-old who fired the initial shot," said Philadelphia Police Chief Inspector Scott Small.
Small said the 24-year-old does have a valid license to carry a gun and that officers recovered both weapons.
Investigators said they are working to gather any possible video surveillance of the incident.
Police have not released the names of anyone involved.