The 19-year-old is believed to have a bright future ahead of him at the Parc des Princes but at present he is down the pecking order under manager Unai Emery.
In a bid to get more first-team experience under his belt, PSG have decided they will allow the playmaker to make the switch to Palermo, who are currently pushing for a return to the Italian top flight.
Callegari does have Italian roots but was born in France and has featured at youth level for the French national side.
Watford are being linked with a summer swoop for Werder Bremen's Sweden international left-back Ludwig Augustinsson.
West Ham are reportedly set to pull out of their plan to sign central defender Alfie Mawson from Swansea this summer.
Brighton have been linked with a swoop on League One Sunderland for the signature of goalkeeper Jason Steele.