Rei's defence lawyer Raukawa Simon claimed the accused had acted in self-defence after being attacked by Taniwha.
Simon said the woman had sworn at Rei, hit him with a spirits bottle, punched him and then chased him with a knife.
The 48-year-old had punched Taniwha so he could escape, she said.
After hearing two days of evidence the jury retired to consider its verdict about 10.50am on Thursday and returned just after 1pm to deliver the decision of guilty.
Judge Krebs convicted Rei, gave him his first strike warning and remanded him in custody for sentencing on May 24.
As Rei was led out of the courtroom he was heard saying "well done Whanganui, well done".
He also called out to a woman in the public gallery "love you babe, don't give up. I will ring you as soon as I can".