Wirihana accepted he caused the wound that led to Mason's death but claimed it happened accidentally in a struggle as he tried to disable the car, which had been driven at him at speed, injuring his partner.
The verdicts followed a 10-day trial before Justice Rebecca Edwards.
In closing statements on Thursday, the jury heard Wirihana had been drinking and socialising at his partner's place on Christmas Eve with family members.
A female became offended by his behaviour and left the address for a nearby bus stop, calling the police several times about her concerns.
The woman told Mason and three other men, including his son who had been driving past, and they all returned to the house to confront Wirihana.
The jury also heard the woman falsely accused Wirihana of assaulting her.
A fight broke out, with punches exchanged on both sides.
The prosecution said Wirihana lay on top of Heke and bit him, then began chasing the two men he was fighting with around the property with knives.
In the midst of the "chaotic scene", Mason's vehicle was driven towards Wirihana then reversed, pinning Wirihana's partner's leg against another vehicle.
The jury earlier heard at one stage Wirihana was hit over the head with a shovel and he was later treated for injuries to his head, face and chest.
Jenson said evidence from several witnesses and Wirihana's comments to the police showed that he was the aggressor that day and in "attack mode".
"'I want to kill people.' These are the words of an angry and agitated Mr Wirihana which left Mr Heke disfigured and Wipatene Mason deceased."
He went well beyond reasonable self-defence in attacking an unarmed man who was no threat to him, Jenson said. The Crown's case was that Mason was not fighting with anyone when he was stabbed.
Even if the jury did not accept the defendant had murderous intent, he must have known his decision to stab Mason was likely to cause his death and "ran that risk anyway".
"Mr Wirihana was looking for payback and used over-the-top violence to get it," Jenson said.
He said the degree of violence also Wirihana allegedly used against Heke when he already had the upper hand was an "aggressive act of violence".
Wirihana elected not to give evidence or call witnesses in court.
His lawyer Adam Holland said the Crown witnesses' evidence at the trial was "riddled with inconsistencies" and untruths.
Holland said that there was no deliberate act by his client to stab the deceased nor any murderous intent on his part - it was an accidental cut as he reached in to disable the car.
"There has been no evidence that Mr Wirihana is some highly-trained assassin, who in the space of few seconds managed to inflict a perfect 2-3cm wide cut to the deceased's neck."
Holland said even the Crown's medical expert confirmed the wound was a soft tissue injury that did not require a significant amount of force and could not determine whether the injury was intentional or not.
"I suggest to you that the injury is more consistent with the chain of events as described by Mr Wirihana in his video interview with the police.
"Despite the Crown claims of Wirihana chasing people around with knives, there was no evidence at the trial to support that contention," he said.
Holland said Wirihana's comment to police about killing people was taken out of context from 45 pages of video interview transcript.
Wirihana told the police that he just wanted to get the other men to stop hurting him and his partner and "it was not just rage, it's fear" for himself and his partner, Holland said.
He also reminded the jury Heke told the police his group had decided to give Wirihana a "hiding" and "teach him a lesson".
Holland said the "harrowing audio" from a 111 call made from the scene by a Crown witness was key evidence.
"We heard the key protagonist in this case respond to a question from the operator
about whether she had seen Wirihana attack anybody with knives, and she replied no."
Holland said a few minutes later a voice can be heard saying 'Aunty, it's so bad, they just won't stop. They've killed Wilson [Wirihana]'.
He said this offered insight into the "extreme level of life-threatening jeopardy" Wirihana and his partner were in after he was "set upon" by a group of men he did not know.
Wirihana will be sentenced on March 22.
