The street value of the drugs is estimated at around €33 million.
Greek authorities have seized more than four tonnes of cannabis hidden in industrial cupcake-making machines.
The processed drugs were found by police in the country's main port of Piraeus, stored in a shipping container heading from Lebanon to Slovakia.
Their estimated street value is €33 million.
The shipment, whose registered contents were three industrial cupcake-making machines, arrived by sea in Piraeus on April 14.
According to authorities, the equipment was due to be transported by rail on April 20 to Bratislava, through North Macedonia, Serbia, and Hungary.
A search was carried out on the container after a tip-off from the United States Drug Enforcement Administration (DEA).
"The inspection revealed that there was, among other machines, an iron tank in which a hidden storage space had been constructed," Greece’s Financial Crimes Squad (SDOE) said in a statement.
"After careful research, a manhole was discovered on the roof of the tank, which opened up to a constructed storage space."
Police said they had recovered 129 nylon bags of processed cannabis, as well as another 282 bulk packages of the drug. In total, 4,387 kilograms of cannabis were confiscated in the bust.
Greek authorities said they received assistance in the case from the drug enforcement agency of Saudi Arabia, as well as the DEA office in Athens.
According to the US, the SDOE Drug Agency received information that a large quantity of narcotics was being moved by sea from the Middle East to Central Europe.
An investigation into the shipment is continuing.