The 19-year-old, who competed at last month's Masters, is due to turn professional ahead of European Tour Qualifying School towards the end of the year.
Murdaca qualified for Augusta National, where he finished as the tournament's third amateur, by winning last year's Asia-Pacific Amateur Championship at the Royal Melbourne Golf Club by a record-breaking margin of seven shots.
Murdaca said: "I'm very excited to be signing with ISM family to manage the next phase of my golf career.
"I'm looking forward to creating a long ongoing relationship with Chubby Chandler and ISM. I can't wait for the journey to begin."
Murdaca follows in the footsteps of fellow Australian Todd Sinnott and New Zealander Ryan Fox, who have also joined ISM in recent months.
ISM's stable includes the likes of Lee Westwood, George Coetzee, Louis Oosthuizen and Joost Luiten.
ISM Chief Executive Officer Chubby Chandler said: "I first met Antonio at the Thailand Golf Championships in 2014 and he's a good, strong player who will have really benefitted from the experience of Augusta.
"We are building a really interesting group of talented young players in Australia and it is an exciting time."
The youngest player to win the Australian Boy's Championship at the age of 14 in 2010, Antonio, from Adelaide, regained that title in 2013, having helped Australia to a first ever victory in the Toyota World Junior Cup.
Murdaca is expected to play amateur events in the UK and the US leading into the US Amateur Championship where he has a start courtesy of his Asia Pacific Amateur victory.
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