Sergeant Budnick with the Perryville Police Department says the accident happened just after 10 p.m. ET Tuesday on Route 40 near Aiken Avenue.
The child reportedly walked into the westbound turn lane of Route 40 when a vehicle, driven by a 69-year-old Perryville resident, hit him.
The vehicle was said to be going about 30-35 mph, Budnick said.
The boy was flown to Johns Hopkins where he is listed in critical condition.
Police say the boy was crossing the street with his family, but they were not in a crosswalk.