The penalty is a hefty one - meaning he will not be back playing rugby league until at least round 23 of the 2015 season.
Auva'a had pleaded guilty to charges of recklessly causing injury when he went to court last week. Souths had initially fined him $2000 and suspended him for seven days when made aware of the incident earlier in the year.
The Rabbitohs said in a statement on Thursday they supported the NRL's stance."We will work closely with Kirisome on his rehabilitation, as we have since the incident occurred back in January," CEO Shane Richardson said.
"As a club we take a very serious view on domestic violence."Kirisome has now received punishments from three different bodies and we will continue our duties to ensure he is educated and supported so as to never commit an offence like this again."
Auva'a had been in Melbourne in January for a wedding when he visited his former partner's home and shoved her to the ground and then swung her into a garage door when he was told he had to sleep on the couch.
While he pleaded guilty to the charge back in May the incident did not attract a large amount of attention because Auva'a was a fringe player with the club. But he went on to cement a regular spot in the Rabbitohs' starting side and was an integral part of their first premiership win in 43 years.
The NRL came under fire in some media circles because of a perceived lack of action over the issue but NRL boss Dave Smith maintained the sport's governing body was allowing due process and was awaiting the court's decision before imposing any further penalty.
Smith said in Thursday's statement that any type of violence against women was simply wrong.
"Let me make it clear we abhor violence against women and it will not be tolerated in our game," Smith said.
"Everyone needs to understand that if you are violent against women there is no place for you in rugby league."
Smith added that if Auva'a re-offended he would be banned from the game permanently.
Former NSW winger Blake Ferguson is still waiting to find out whether he will be re-registered by the NRL after being found guilty of groping a woman in 2013.
Ferguson, who also had no conviction recorded, has just been allowed to train with the Sydney Roosters but has not been re-registered by the NRL.
Two years ago Queensland Cowboys halfback Robert Lui was suspended for most of the 2012 season after pleading guilty to the assault of his partner the previous year.