The incident happened around 11:40 a.m. Saturday on Interstate 95 in Peabody, The Boston Herald reported.
The boy, whose name was not reported, called 911 after his father had a seizure. While on the phone with a dispatcher, he managed to steer the car into the breakdown lane and then apply the breaks, police said.
When police arrived, the father was unconscious and was taken to Lahey Clinic in Peabody. He is now in good condition, police said.
"It's absolutely amazing what this young man did," state police spokesman David Procopio said. "To see a child with the poise and quick thinking to do that is just amazing."
"We're very happy to hear his dad is doing well. This very well could have ended differently had the boy not reacted as he did. We plan to nominate the young man for a lifesaving award," Procopio said.