Muscat said family reasons were behind his decision to leave the Phoenix after eight seasons with the New Zealand club.
“Rebecca is expecting our third child on July 2 and we decided it was time to move back to the family,” Muscat said.
“In the A-League you travel every second week and it will be good for Becks to have her family around her.
“We also have a house there waiting to be lived in so the move will be easy.”
Muscat, 31, has amassed 186 games for the Phoenix - second only to 200 game veteran Andrew Durante - and has represented Malta nine times after an international debut in 2009.
“He is a man of action, hard on the field, but get him off it and he is the perfect gentleman,” Phoenix coach Ernie Merrick said.
“Manny has been a valuable player for our club because he can play any position in the backline and do it well and is also a very good holding midfield player.
“He is an all-round good quality player, a great competitor and good on-field leader; always committed at training and happy to do community work for the club.
“We will miss him but he goes with our best wishes and I wish him well in his new venture.”