Hackenberg has been a free agent since clearing waivers after being released by the Oakland Raiders in May.
The Raiders had traded for Hackenberg, acquiring him from the New York Jets.
The 23-year-old Hackenberg was a second round draft pick by the Jets in 2016 out of Penn State.
Despite that lofty draft status, Hackenberg has never thrown a pass in a regular season NFL game.
Hackenberg will provide another quarterback in the Eagles stable of signal-callers. Injured starter Carson Wentz hopes to return from a knee injury by Week 1.