The 34-year-old former Torino and AEK Athens keeper joined Palermo on loan until the end of the 2012-13 season with a view to helping the Sicilians retain their Serie A status. He made 15 appearances and conceded 15 goals.
Despite improving results, the Rosanero would ultimately return to Serie B after nine years away, but Sorrentino will remain at the Stadio Renzo Barbera for a tilt at promotion.
A statement published on palermocalcio.it read: "Palermo have exercised their right to take full ownership of Stefano Sorrentino from Chievo."
Chievo also confirmed conceding their half of Sorrentino's registration, adding that the keeper now "fully belonged" to Palermo.