Saxon Dio Edwards (33) sat listening to his victim’s evidence for two hours in a trial which began before Judge Duncan Harvey.
The guilty pleas came following the lunch break, after the Crown withdrew evidence in relation to four charges.
Edwards admitted assaulting a female on December 5, and three charges of assault with intent, three of assault with a weapon, two of male assaults female and one of kidnapping, all in Invercargill on December 8, 2020.
Former girlfriend Tia Matika, the victim in the case, said she had known Edwards since they were children.
She was trying to break up with him at the time he attacked her in December 2020.
After pushing her at a party, three days later Edwards came to her house - a house she shared with her cousin and her two children - in the morning demanding to be let in.
She let him in because she did not want a drama.
After having a cigarette outside in the sleepout, she went back to her bedroom and he followed.
She said she then "guarded up" with a pillow.
When asked by Crown prosecutor Mike Brownlie why she did that she replied, "I knew what was coming."
"What was coming?" Mr Brownlie asked.
"He was going to hurt me," she replied.
After calling her a snitch, a liar and a sexist slur, he started punching her in the head, arm and legs.
He then began to prick her on the chin with the butcher’s knife.
When she asked him to stop he told her to shut up.
He then picked her up by the hair and used the knife to cut her hair off.
He also sliced the top of her index finger off when she put her hand up to fend him off.
She tried to get out of the room but he stopped her by blocking the door and started hitting her again.
She got out of the room when he asked her to get some cannabis from her cousin, but he kicked her and punched her because she had no pants on, she said.
When he continued to punch her later he did it while wearing a knuckle-duster, she said.
The jury adjourned for lunch, and on return was dismissed after Edwards pleaded guilty to the reduced charges.
Judge Harvey reassured the members of the jury they had not wasted their time as sometimes it took a defendant hearing evidence to change their mind and decide they did not want to go any further with a trial.
Saxon was remanded in custody to appear for sentencing on April 29.
