The gang members were found guilty of aggravated assault of at least eight people.
In May, they had crashed a private party held by a motorcycle club in Kalmar, southern Sweden, and proceeded to beat up some party-goers while others were forced to watch.
The Gothenburg District Court also found the men guilty of theft and causing property damages, wrote the TT news agency.
The prosecutor originally brought charges against 19 men, but four were released without conviction.
The court verdict stated that the Hells Angels went on the rampage simply to damage the rival club and its members.
It further said it was part and parcel of organized crime.
The prosecutor had argued the men should be given a four-year sentence, as the attack also involved theft of the rival gang members phones and cash.
The court found, however, that the men were more intent on humiliating their victims rather than stealing from them.
The charge of aggravated theft was thus downgraded to theft.
In support of the verdict, the court noted that the men had thrown away the haul rather than take it with them.