Chris Ball, 39, was allegedly "sucker punched" outside a Fort St. John bar in July 2012 and fell over, hitting his head on the pavement. He was later taken off life support at an Edmonton hospital.
A jury delivered a verdict on Friday after a 10-day trial in Fort St. John.
Joel Christopher Marchand, 31, was found guilty of manslaughter and assault causing bodily harm. Marchand has not yet been sentenced.
Ball was working in the oil and gas industry in northeastern B.C. at the time of his death.
His brother Jon Ball said Tuesday the family is pleased with the manslaughter conviction, but they are still shocked and angry about what happened.
"I'd rather have my brother here than something like this, I can tell you.... The last year and a half has just been a complete whirlwind. It was such a shock to all of us that we haven't really moved on much."
Another man, Ted Metcalfe of Kelowna, B.C., was also initially charged in relation to Ball's death. Those charges were stayed last year.