Archbishop Charles J. Chaput said the closings, recommended by a special commission that has been studying the schools for more than a year, are necessary to keep Catholic education viable, The Philadelphia Inquirer reported.
"We cannot sustain unsustainable schools," he said.
Other schools in the diocese will be affected by the change, as some are converted to regional schools. Officials said more than 20,000 students will be affected.
The diocese has 17 high schools and 156 elementary schools in Philadelphia and its suburbs. Philadelphia will lose two high schools and 33 elementary schools will be merged into 14 regional schools.
Declining enrollment and growing deficits are responsible for the decision, officials said. The deficit averages almost $320,000 per school.