The court in Yangon on March 5 handed down death sentences to 15 of those arrested, the court official told Reuters.
"Judgement was passed under tight security for fear of reprisal," the official said on condition of anonymity because of the sensitive nature of the case.
The official declined to divulge the motive for the attack, but a lawyer familiar with the case said it was related to a dispute between criminal gangs.
Ko Kyaw Min, 32, was attacked by masked men inside a restaurant on November 17, 2011. He fled into the street where another group of men stabbed him to death, according to the court official.
Those convicted have one month to appeal against their sentences, the official said.
Death sentences in Myanmar are most often commuted to life imprisonment. The last execution took place in 1988.