Garuccio joined the club when they were known as Melbourne Heart as a 17-year-old in 2012.
He played 45 times for City during his four seasons in Melbourne before heading to Adelaide United in 2016 and then to Scotland in 2018 to join Heart of Midlothian.
The Adelaide born defender made 29 appearances in Scotland, scoring once and assisting five times.
Melbourne City Director of Football Michael Petrillo said he was delighted to have Garuccio return to the club with more experience.
“He returns to us as a battle-hardened senior footballer and we know his European experience will have readied him to be a major asset to our side moving forward," Petrillo said.
“(Coach) Patrick [Kisnorbo] has an in-depth understanding of Ben’s attributes – playing alongside him during his first stint at the Club – and we feel he’s a perfect fit for our style, playing as a full back or further up the field in a more attacking role.”
Garuccio, who has represented Australia at Under-20 and Under-23 level, said he was happy to return to Australia.
“I’m delighted to be back at Melbourne City and can’t wait to return to AAMI Park to play in front of our home fans,” Garuccio said.
“I made my senior debut for the Club so Melbourne City is a special place for me. I know what it means to the fans and the people at the Club to achieve the ultimate success and hope we can accomplish it as a team.”
Garuccio is the club’s sixth signing of the 2020-21 pre-season joining Andrew Nabbout, Marco Tilio, Matt Sutton, Taras Gomulka.
