Kaihau smiled and looked at family members in the public gallery as the jury of six men and six women deliberated for a little over three hours before delivering their unanimous verdict finding him guilty of manslaughter.
Justice Robert Dobson remanded Kaihau in custody for sentencing date likely to be in November.
Earlier, Crown prosecutor Ross Douch said Kaihau was an "inherently unreliable" witness who had "lied and lied and lied".
Kaihau had tried to hide evidence that would implicate himself in the killing, and a week later he tried to fool a Waihi detective into believing his bogus alibi that he was at home at the time of the incident, Mr Douch told the court.
"In the face of mounting evidence he remained steadfast, becoming even belligerent or indignant, at the proposition that gives you an indication of how far he will go."
Mr Douch said despite Kaihau's argument that he reacted instinctively when he claimed Mr Wilkinson stood on his injured leg, he did not let out a yell in pain.
"Isn't that funny that was without a sound ... all Mrs Wilkinson heard was her husband then this terrible bang.
"There was no yelp, no cursing ... isn't that remarkable that he suffered in silence?"
He said Kaihau was carrying a knife that "wasn't a toy or innocuous" and his level of intoxication was not so bad that he would be "incapable to realise" that it was not a dangerous weapon.
The knife, which has not been recovered, was believed to have been at least 8.5cm in length and 3.5cm in width at its midpoint.
By targeting Mr Wilkinson's head he could only have had murderous intent.
But Kaihau's lawyer Paul Mabey QC said his client was not on trial for lying to police or hiding evidence and a manslaughter verdict should be returned.
Mr Mabey said the evidence showed Kaihau was in a happy mood on the evening in question, and there was no suggestion prior to his altercation with Mr Wilkinson that he was aggressive or looking for trouble.
"How does a happy, drunken young boy become a cold blooded killer because a householder says to him 'I'm going to report you'?"
