Criminals were set to make a fortune from 3 tonnes until police swooped.
Six men have been charged after police seized almost three tonnes of narcotics worth more than A$1.5 billion ($1.62 billion) in Australia's second largest drug bust.
The illicit drugs concealed in furniture include 1917kg of MDMA and 849kg of methamphetamine.
Australian Federal Police Commissioner Andrew Colvin said the MDMA was in various forms, but mostly powder.
NSW Police say MDMA, popularly known as Ecstasy or, more recently, as Molly, is a synthetic, psychoactive drug.
NSW Commissioner Andrew Scipione said the seizure would have a serious impact on organised crime.
"When we talk about two tonnes of MDMA, we're talking upwards of 10 million individual doses, tablets," he said.
Customs chief executive Roman Quaedvlieg said officers found the drugs in a sea cargo container that arrived in Sydney from Hamburg in Germany last Friday. Colvin said it was the largest Australian seizure of methamphetamine and the second largest of MDMA.
He said police managed the delivery of the narcotics to try to identify as many of the people involved as possible.
Police are also working closely with the German federal police and Interpol. He said the investigation would probably determine a number of organised crime groups involved in the delivery.
Scipione said: "The notion of stopping the importation is one thing, but the message that needs to go to those that are in the business of importing these drugs is just as important.
"My advice is go somewhere else, go to another country. Don't bring your evil poison here to Australia."
Quaedvlieg said last year across the main drug types Customs seized about five tonnes at the border.
This year they were likely to find more.
The arrested men are Australian residents aged from 23 to 34.