Norma Davis, 58, of Yeadon was charged with endangering the welfare of a child and reckless endangering.
Police in Upper Darby said Davis picked up the child, along with two other children, from the Park Lane Elementary School in Darby and took them back to the PNP Family Play Center at 53 N. Union Ave.
It was around 6:00 p.m. when the child's mother came to pick him up, Police Superintendent Michael Chitwood said, and was told the child wasn't there.
"So they go about and look in the automobiles and laying in the back seat, unconscious, is the 5-year-old," Chitwood said.
Chitwood said the child was taken to Children's Hospital of Philadelphia in critical condition. He has since been upgraded to good condition.
"Half an hour longer and we'd probably be looking at a homicide," said Upper Darby Police Superintendent Michael Chitwood.
Davis is free on $50,000 bail after spending the night in jail.
The daycare is licensed by the New Jersey Department of Welfare. However, a review of inspection records found that the facility had 30 incidents of non-compliance in 2012.
In one case, 12 kids were left unattended in a room. In another, it was found that the facility didn't have a proper emergency plan.
All of the violations were corrected.