The 16-year-old, who wiped back tears after the verdicts were read, admitted stabbing him but unsuccessfully claimed it was self defence.
But the jury found otherwise, and although deciding she did not have murderous intent, they agreed she killed Kingi unlawfully by way of stabbing.
The public gallery remained quiet as the verdicts were read.
The jury was sent to begin their deliberations at midday before returning three hours later with their verdicts.
Earlier, Justice Timothy Brewer explained how self defence worked in terms of the law.
He told the jury of five men and seven women they had to put themselves in the shoes of the accused and whether she was justified in stabbing Kingi.
Not only that, if they did find it was a justified action, they then had to decide whether the degree of force was reasonable given the circumstances the accused believed them to be.
Her defence counsel, Ron Mansfield, submitted that she felt Kingi was a threat – he was drunk, angry and advancing on her and her instinctive reaction to protect herself was to pull out the knife and stab him.
However, the Crown said the accused's actions were not reasonable and Kingi was simply in her way when she tried to rescue her friend, so stabbed him out of anger, rather than fear.
The older accused had options that night, including running away either before or after the younger accused hit Kingi on the head with a screwdriver or pulled the knife and simply threatened him with it, rather than plunging it into his chest.
As for what was a reasonable amount of force, that could only be decided by the jury, the judge said.
As she was charged as a party to murder, the younger accused could not be found guilty of a more serious charge than her co-accused.
She is also subject to special legislation involving young people - aged 10 to 14 - which has a special clause stating they also had to be sure she knew her actions were "wrong or contrary to the law".
Her defence counsel Roger Laybourn submitted she was not guilty of either murder or manslaughter as not only was she too young to comprehend what was happening, she had only met her co-accused that night and she was standing about 2m behind her when the stabbing took place.
The 16-year-old was convicted by Justice Brewer and remanded in custody for sentencing in December.
In light of the verdicts, the 14-year-old was granted permanent name suppression by the judge. The older accused had her interim name suppression carried over until her next appearance.
Kingi's family declined to comment outside court, but through Detective Inspector Graham Pitkethley they said they accepted the jury's verdicts and were just pleased that someone had been held to account for his death.
