Federici, capped 16 times for the Socceroos, returns Down Under after a two-year spell with Championship side Stoke City and nearly two decades in English soccer.
"Adam's knowledge and experience in the top European leagues will be invaluable to our squad," Macarthur coach Ante Milicic said in a statement on Thursday.
"The opportunity to strengthen our roster with someone of Adam's ability and professionalism doesn't come around often."
"To be able to come back to Australia and play football, not only at a start-up club, but also only 90 minutes from where I grew up is something I could not pass on," said the 35-year-old.
Milicic, former head coach of the national women's team, has been on a recruitment drive to sign overseas-based Australians for southwest Sydney's Macarthur, who will join the A-League in the 2020/21 season.
(Reporting by Ian Ransom; Editing by Peter Rutherford)