The men were each sentenced to one year in prison and ordered to pay 30 million kronor ($3.56 million) in damages between them.
Representatives of the entertainment industry in Germany rejoiced at the verdict.
Head of the German Music Industry Association Stefan Michalk said on Friday in Berlin it makes clear that such sites have “nothing to do with romantic views of buccaneering, but are actually a modern form of theft with which the operators – for example with advertising revenue – personally get richer.”
Meanwhile the head of the German Culture Council Olaf Zimmerman said the verdict was an “important victory” in the battle to secure the rights of creators and other copyright holders. “But the frightening thing is that there may already be similar websites ready at the gates, where organisers will make other tools for burglary available,” he said.
The trial has attracted international attention, with file sharers and copyright holders around the world wondering what sort or precedent may be set.
"By providing a website with ... well-developed search functions, easy uploading and storage possibilities, and with a tracker linked to the website, the accused have incited the crimes that the file-sharers have committed," the court said in a statement.
Founded in 2003, The Pirate Bay makes it possible to skirt copyright fees and share music, film and computer game files using bitTorrent technology, or peer-to-peer links offered on the site.
None of the material can thus be found on The Pirate Bay server itself.
The four, who have denied any wrongdoing, are expected to appeal the verdict and have previously vowed to take the case as high as the Swedish Supreme Court if necessary.
The Pirate Bay claims to have some 22 million users worldwide, and according to public prosecutor Håkan Roswall, The Pirate Bay produced annual earnings of around 10 million kronor ($1.2 million).
Despite the verdict, the website is still operating.