Benjamin Togiai was struck in the chest and killed outside the Big Time Boxing event at the Melbourne Pavilion on March 1, 2019.
Another man, Omar Bchinnati, required emergency surgery to remove a bullet from his leg.
The two shooters, Abdullah El Nasher and Osamma Allouche, pleaded not guilty to the charges of murder and attempted murder.
They took the case to trial in the Victorian Supreme Court, arguing they were acting in self-defence.
But a jury on Monday found El Nasher guilty of murder and causing serious injury intentionally.
Allouche was found not guilty on the charges of murder and attempted murder, as well as alternative offences.
Mr Togiai's father Faatau said he was relieved at El Nasher's guilty verdict.
"We're so happy, we're so overwhelmed with the result today," he told reporters outside the Supreme Court.
"We miss our son. Our heavenly Father knows the truth and he knows everything in our heart."
The jury was told there was tension at the boxing event between El Nasher's group on table 28 and another group on table 64 that included Mr Togiai and Mr Bchinnati.
Soon after arriving, El Nasher left and returned to his car to arm himself before turning his phone off or putting it on airplane mode to disguise his location.
He then used another phone or directed someone else to contact Allouche on his behalf, instructing him to come to the Melbourne Pavilion.
El Nasher was outside the main door when Allouche arrived and the pair ducked in and out together a couple of times before El Nasher headed across the road and Allouche went inside alone.
The jury was told that was a signal to their group that a confrontation was about to begin.
Just before 10pm the groups on tables 28 and 64 were booted out by event organisers, only referred to in court as Mr Gatto and Mr Haddara.
As they gathered outside, El Nasher ran across the road and fired several shots. Allouche allegedly fired a single shot and then El Nasher fired again.
Mr Togiai was hit once in the chest with a bullet and died at the scene, while Mr Bchinnati required emergency surgery after being shot a single time in the thigh.
Mr Togiai's sister Jolene said her brother would always be remembered as a strong father and family man who was the life of the party.
"His daughter will grow up knowing that her dad was a good man," she told reporters.
"She misses him so incredibly much. She talks about him all the time and so at least there's some justice for her as well."
Both Allouche and El Nasher were remanded in custody following the verdict.
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