Special Operations teams (SEK) from six different federal states were involved in the operation, reports the Frankfurter Allgemeiner Zeitung (FAZ).
Upon searching the suspects' homes, police found weapons including pistols, revolvers, and a shotgun.
Based in the impoverished southern region of Calabria, the 'Ndrangheta is said to be behind most of Europe's cocaine business, and is regarded as the most powerful mafia organisation in Italy.
The suspects in Tuesday's arrests are between the ages of 40 and 69.
Police carried out the arrests in coordination with authorities in Italy, who also arrested two members of the 'Ndrangheta organization on Tuesday.
“The reason for the arrests was a mutual assistance request from Italy and a European arrest warrant.
"Unfortunately we know very little about the charges against the men,” a spokesperson for the general prosecutor in Karlsruhe told FAZ.
The general prosecutor in Karlsruhe has now applied to the district court for an exportation order, writes the Südkurier.
This is not the first time that the beautiful southern lake has made headlines in connection with Italian crime syndicates.
In March 2011 police arrested five Italians at Lake Constance as part of an international operation against the mafia that included 30 arrests over three continents.
In August 2014 the general inspector for organised crime in Baden Württemberg, Sigurd Jäger, described Lake Constance as a “stronghold” of the mafia, the Thurgauer Zeitung reported at the time.