It took more than an hour and 40 minutes to read aloud the court's lengthy verdict on Monday, including the acquittal of 131 other defendants.
The drama unfolded in a bunker-stye courtroom in the southern Calabria region, where the mob organisation was originally based.
The 'Ndrangheta has quietly amassed power in Italy and abroad as the Sicilian Mafia lost influence and now holds almost a monopoly on cocaine importation in Europe, according to anti-Mafia prosecutors who led the investigation in southern Italy.
The organisation also has bases in North and South America and is active in Africa, Italian prosecutors maintain, and 'Ndrangheta figures have been arrested in recent years around Europe and in Brazil and Lebanon.
The defendants had been charged with crimes that include drug and arms trafficking, extortion and Mafia association, a term in Italy's penal code for members of organised crime groups.
Others were charged with acting in complicity with the 'Ndrangheta without actually being a member.
The charges grew out of an investigation of 12 clans linked to a convicted 'Ndrangheta boss.
A vast bunker was built in an industrial area in Lamezia Terme to house the proceedings.
The central figure, Luigi Mancuso, served 19 years in an Italian prison for his role in leading what investigators allege is one of the 'Ndrangheta's most powerful crime families, based in the town of Vibo Valentia.
Vincenzo Capomolla, deputy chief prosecutor of Catanzaro, said prosecutors' overall case held up with the convictions and confirmed the "deep-rooted, widespread and alarming" stranglehold the 'Ndrangheta held on Vibo Valentia.
Giuseppe Di Renzo, a defence lawyer for several of the defendants, noted that more than a third of the original defendants were fully acquitted, while others were found not guilty of some charges.
He criticised the disparate and large number of defendants, saying they showed there was no cohesive thread to the prosecutors' case.
But Catanzaro's former chief prosecutor who launched the investigation, Nicola Gratteri, said Mafia trials often had to cast wide nets because of the very nature of how the criminal syndicates operated.
The trial took place in a specially built high-security bunker in Lamezia Terme, which is so vast that video screens were anchored to the ceiling so participants could view the proceedings.
Based almost entirely on blood ties, the 'Ndrangheta was substantially immune to turncoats for decades, but the ranks of those turning state's evidence are becoming more substantial.
Despite the large number of defendants, the trial was not Italy's biggest one involving alleged mobsters.
In 1986, 475 alleged members of the Sicilian Mafia went on trial in a similarly constructed bunker in Palermo.
The proceedings resulted in more than 300 convictions and 19 life sentences.
