Shivan M. was sentenced to 16 years in jail for killing one of the brothers, Vigan M., and leaving the other with life-threatening injuries, according to media reports.
The verdict came after a two-day trial at which the prosecution called for a 20-year prison term.
Two co-accused were convicted of lesser charges.
The killer expressed regret for his action, apologising to his victim’s family and friends, according to 20 Minuten online.
In addition to his jail sentence, Shivan M. has to pay 235,000 Swiss francs in compensation to the dead man’s family.
The case dates back to July 2012 when a fight broke out between the brothers and Shivan M. at the Kaufleuten club in Zurich.
Vigan M. had been celebrating his 23rd birthday with his brother and friends.
Shivan M. is said to have returned to the scene with a knife and inflicted numerous stab wounds on the brothers, resulting in Vigan M.’s death.
He was arrested at the end of July 2012 in Norway, where he fled immediately after the killing, and was extradited to Switzerland.