The haul, estimated to have a street value of A$1bn (£600m; $800m), was uncovered when police raided a dock in Western Australia, authorities said.
Police have charged the men, each of whom faces a maximum penalty of life in prison.
Crystal methamphetamine, also known as ice, has been described as the most damaging illicit drug in Australia.
The 1.2-tonne (2,650lb) bust was larger than the previous record seizure, made in Melbourne in April.
"We are very pleased that 12 million hits of methamphetamine will be off the streets over the Christmas [and] new year period," said Home Affairs Minister Peter Dutton.
Six men were arrested at a dock near the city of Geraldton, while two were arrested in Perth. All are Australians aged between 33 and 52
The arrests happened after 59 bags containing the drugs were loaded from a boat, Valkoista, into a white van on Thursday, Australian Federal Police said.
In 2015, Australia's government established a national taskforce to tackle the growing use of ice.
The move followed a report by the Australian Crime Commission that found ice posed the highest risk to communities of any illegal substance.