German officials discovered 16 tonnes in five shipping containers that had arrived in the port of Hamburg from Paraguay earlier this month.
Police in the Netherlands were notified and a further 7.2 tonnes of cocaine was seized at the Belgian port of Antwerp.
German officials said the cocaine had a street value of billions of euros.
A 28-year-old man suspected of involvement in the trafficking of the drugs has been arrested in the Netherlands, Dutch police said on Wednesday.
The two raids, which took place earlier this month, resulted in the seizure of an "enormous amount of cocaine", customs officials said.
In Antwerp, the drug was hidden in a container filled with wooden blocks from Panama.
The cocaine found in the northern German city of Hamburg was concealed in tins of wall filler, which had entered Europe on a container ship from Paraguay.
Customs officers decided to take a closer look at the Paraguayan containers after noticing "clear irregularities" with some of the contents - tin cans that were meant to be filled with putty.
"Beyond a layer of genuine goods, packed just behind the container door, numerous tin cans were in fact filled with other goods," officials said.
Investigators then ordered the containers to be unloaded, and found cocaine stashed away in more than 1,700 tins.
"This is the largest amount of cocaine ever seized in Europe and one of the largest single seizures worldwide," German customs said, referring to the Hamburg haul alone.
"We are estimating a street sales value of between €1.5bn and €3.5bn ($1.8bn and $4.2bn) for the 16 tonnes," Hamburg customs official Rene Matschke told AFP news agency.
Hamburg is Europe's third biggest port, and the largest in Germany.
Paraguay has been a key transit country for drugs for years.
Powerful drug trafficking gangs from neighbouring Brazil, such as First Capital Command (PCC), have expanded across the border into Paraguay and are running many of the smuggling operations there.
The drugs are often shipped in containers from Paraguay to port cities in Europe.
This latest haul, however, is the biggest ever discovered in Europe.