The 19-year-old Parma defender is one of two uncapped players - along with Melbourne City goalkeeper Tom Glover - in Arnold's squad for the June 15 friendly against Argentina in Beijing.
Circati, who was raised in Perth, has played for Italy's youth teams in the past and spent the past year mulling his long-term international future.
But like dual-eligible Manchester City youngster Alex Robertson did earlier this year, Circati recently phoned Arnold to say he was ready to go all-in with the Socceroos.
"It's been 12 months of communication with the kid and he had two big decisions to make," Arnold said.
"He said he wants to play for Australia, his heart has told him he wants to play for Australia and his passion to come in straight away was great.
"After the World Cup there's a lot of hype around football in Australia."
Arnold is confident former Adelaide youngster Mo Toure (Guinea) of Reims, and Roma's Sydney-born playmaker Cristian Volpato (Italy) will also follow the lead of Robertson and Circati.
"I'll get across to Europe in early August and meet them face to face," Arnold said.
"I think what they saw at the World Cup has inspired them.
"I think that happened with Alessandro and they're all mates and they talk to each other as well."
Circati and Glover, who has edged out World Cup qualifying hero Andrew Redmayne, headline the new additions to a refreshed Socceroos outfit.
Experienced campaigners Aziz Behich, Jason Cummings, Milos Degenek, Craig Goodwin, Jackson Irvine, Aaron Mooy and Bailey Wright are all unavailable due to injury.
A number of promising players, including Marco Tilio, Garang Kuol and uncapped Central Coast Mariners defender Nectar Triantis have been kept out of the Socceroos squad and will instead feature for the under-23s in the Maurice Revello Tournament in France.
The tournament is seen as a vital tune-up for Olympic qualifiers in September.
Arnold has long stressed the importance of qualifying for the Olympics, viewing next year's Games in Paris as a key preparation tool for the 2026 World Cup.
Among those to profit from the list of absences are the recalled trio of defender Gianni Stensness, leftback Joel King and midfielder Denis Genreau, who has been impressing in the French top flight with Toulouse.
Adjin Hrustic is also included after missing the March window with an ankle injury,
"(Genreau) is doing exceptionally well and it was a tough decision for me to leave him out of the World Cup," Arnold said.
"It's important that you reconnect with the kid as soon as possible.
"If there's one little bit of a payback for some of them that were left out of the World Cup is they get to play against Argentina."
Arnold has given recently-departed Wellington Phoenix boss Ufuk Talay a one-off cameo on his coaching staff for the rematch with the Argentines, who knocked Australia out of the World Cup at the round-of-16 stage.
Socceroos squad:Â
Goalkeepers: Mat Ryan, Tom Glover, Joe Gauci
Defenders: Nathaniel Atkinson, Jordan Bos, Alessandro Circati, Joel King, Kye Rowles, Gianni Stensness, Harry Souttar, Ryan Strain
Midfielders: Keanu Baccus, Cammy Devlin, Denis Genreau, Ajdin Hrustic, Riley McGree, Connor Metcalfe, Aiden O'Neill, Alex Robertson
Forwards: Brandon Borrello, Mitch Duke, Jamie Maclaren, Mathew Leckie.
