The Bangkok Criminal Court found Santika nightclub owner Wisuk Sejsawat and company executive Boonchu Laosinart guilty of causing the deaths of other persons without intent.
More than 1,000 revelers were inside the club when an indoor fireworks display set off after the countdown to New Year ignited the blaze. The fire raced through the two-story building, sending panicked guests running for the main entrance.
Victims -- including three Singapore, one Japanese and one Myanmar national -- died of burns, smoke inhalation and from being crushed in the stampede to get out. More than 100 people were injured.
Dozens of the injured victims and relatives of the dead were in the courtroom Tuesday to hear the verdict. Fifty plaintiffs jointly filed the case against the defendants.
"I feel better now that justice is served," said Taworn Promtong, whose 24-year-old daughter died from injuries sustained in the fire. "But my family was never the same without our eldest daughter. There's a void that could never be filled."
The verdict did not deal with allegations made soon after the fire that police had turned a blind eye to safety violations at the club prior to the fire.
Four other persons were acquitted, including Sarawut Ariya, the lead singer of a rock band named "Burn" that was playing when the fire began. He was accused of setting off some of the fireworks that started the fire, but the judge ruled that videotaped evidence showed he was not responsible.
The court also ordered Boonchu's company to pay 8.7 million baht ($255,500) in compensation to the victims or their families.