Court documents said Ronald Kelly, 26, was inside the home with his mother, her ex-boyfriend and other family members in the early hours of May 19 when the incident unfolded.

The court heard Kelly's mother was downstairs watching TV with her ex-partner when he propositioned her for sex.

She refused and the pair got into an argument, with the man allegedly producing a knife.

"Oi, he's gonna stab me, he's gonna stab me!" the victim yelled out, prompting Kelly, who had been upstairs, to come rushing into the lounge room.

Kelly punched the man a number of times before turning on his mother, grabbing her by the hair with both hands and dragging her to the floor.

He then reefed her back onto her feet by the hair and slammed her head into a shelf under the sink before again slamming her head into the corner between the cupboard and the oven.

Kelly's sister yelled out to him "don't Ronald, don't. What the f--k are you doing?"

The victim put her hand over a deep gash in her forehead and said "ring the ambulance, I'm bleeding" as blood ran through her fingers and down her arm.

Meanwhile, Kelly and his partner left the house.

The victim was taken to hospital by ambulance where she underwent plastic surgery to repair a large, deep gash on her forehead and repair a tear to her upper left ear.

Doctors later told police the woman's wounds had healed completely when she went in for a check-up 10 days later however she may experience difficulty raising her eyebrow in the future and may have long-term scarring and numbness from the trauma.

Kelly was arrested at his home address 12 hours after the incident and charged with recklessly causing grievous bodily harm.

However, Kelly pleaded guilty in court last week to a lesser charge of reckless wounding in a plea deal with prosecutors.

He will face sentencing on December 13.