The Union County Prosecutor's Office says the child was sleeping in the 2008 Dodge Avenger when it was stolen from in front of a business in Union Township around 5 p.m. Wednesday. The car's owner had gone inside.
About 15 minutes later, the car thief dropped the child off with a security guard at Newark Beth Israel Medical Center and left.
Authorities say the boy was unharmed and was soon reunited with his family.
The vehicle has not been recovered.