After being included in the Socceroos' World Cup train-on squad for Brazil 2014, the 23 year-old started the season as Newcastle's No.1 but has not played since being overlooked in favour of Ben Kennedy - who recently signed a new two-year contract - in Round 8.
Birighitti - who remains contracted to the Jets until the end of the 2015-2016 A-League campaign- flies to Italy today to finalise the loan deal that expired at the end of June.
The loan contract includes an option for Varese to buy Birighitti and make the move permanent.
Birighitti follows defender Sam Gallaway and Argentine playmaker Marcos Flores out of Newcastle during the transfer window while Northern Ireland import Jonny Steele was released in December.