Authorities say the 1,728kg (3,800lb) stash - the largest ever intercepted drug shipment to Australia - was found in January at a port in California.
The haul is said to be equivalent to 17 million doses and worth an estimated A$1.29bn ($910m; £705m).
Three of those arrested appeared at Melbourne Magistrates Court on Friday.
Among the suspects are two Americans: a 52-year-old man and a 46-year-old woman. Australian Federal Police (AFP) say they were found with "hundreds of thousands of dollars of proceeds of crime" during a raid in Melbourne.