It happened around 8:30 a.m. on East Baltimore Avenue at Jackson Street in Clifton Heights.
Police say the woman, in her 50s, and the 5-year-old boy were trying to cross E. Baltimore Avenue when they were struck by a car trying to pull into the K-Mart store.
The woman was taken to the Hospital of the University of Pennsylvania, while the boy was taken to Children's Hospital of Philadelphia.
Both were listed in serious condition.
Police say the driver did stop at the scene and is cooperating with investigators.
There was no immediate word on any charges in this case.
The names of those involved have not been released.