Green guided North Queensland Cowboys to their first National Rugby League (NRL) premiership title in 2015.
As a player, he made 162 appearances across five different clubs during a 10-year career, before retiring in 2004.
At the time of his death, he was the head coach of Queensland in the State of Origin Series.
Queensland Police said there were "no suspicious circumstances" around Green's death and that a report will be prepared for the coroner.
Green's family said they are "devastated" by his loss.