It will move to its new home, which is nearby, next fall after completing renovations. The charter is using bonds to finance the project.
Virginia Neiswender, chair of the charter's board of trustees, said in a statement: "We underwent a thorough process to select a new home, and we are excited to move into a site with such a rich history."
The archdiocese closed the boys' school, known as North Catholic, in June 2010 because of declining enrollment and rising costs.
A group of alumni had sought to keep the building open as a private Catholic academy that would be part of the national network of Cristo Rey schools.
Supporters of the Cristo Rey educational model for low-income students say they plan to open a privately funded Catholic academy on Broad Street in Olney in August 2012.
A spokesman for Mariana Bracetti said the charter, which leases its current building, had been looking for a new permanent home for three years.
Contact staff writer Martha Woodall at 215-854-2789 or firstname.lastname@example.org.