Parsons' family issued a statement through police this afternoon.
"The family of Kain Parsons wishes to advise that tragically he has succumbed to the brain injury he received at the Fight for Christchurch on Saturday 3 November," it says.
"We wish to acknowledge and thank the amazing team in the ICU ward at Christchurch Hospital, the paramedics at the event, along with the many doctors, nurses and medical professionals who left their tables to quickly come to Kain's aid.
"The outpouring of heartfelt support from family, friends, colleagues and the public has been humbling and very much appreciated.
"Kain gave his life in the pursuit of raising money for those less fortunate and his enormous heart, selfless attitude and gentle giant nature will leave a void in the lives of so many.
"Kain is survived by his wife and three beautiful children who will miss their family man more than words can express."
A Givealittle page dedicated to raise funds for the Parsons family has already raised more than $30,000. It is still pending moderation by Givealittle.
The boxing event's promoter Callam Mitchell said in a statement that he and his team were devastated.
"On behalf of the entire Fight for Christchurch community, we extend our sincere condolences to Kain's family, friends and workmates," he said. "Our thoughts are naturally also with Kain's opponent during this incredibly difficult time."
Mitchell said he had spoken to Parson's coach, Alfeld and Alfeld's coach, and they were "completely traumatised" by the incident.
"We have already reached out to police, providing our full co-operation into their investigation of what happened."
President of the New Zealand Professional Boxing Association (NZPBA), Pat Leonard, said "everyone is in shock".
"We are very, very sorry to hear about it and we send our utmost condolences to Kain's family," Leonard said.
"This is the first incident in our national association's history where a fighter has suffered a critical injury in the ring.
"We've been in close contact with the promoter since Sunday and can find no fault with the processes that Fight for Christchurch follows."
The news has rocked the boxing community, sparking calls for urgent safety changes.
Boxing New Zealand coach John McKay earlier said the incident was a tragic turn of events and something that needs to be dealt with on a wider level.
"I think corporate charity bouts need to be tightened up in terms of the requirements before they get in the ring to fight."
McKay said requirements should include full medical assessments and a declaration of fitness.
"What we also need to do is restrict the age limit. I don't know how old this guy was but I would think anybody over the age of 45 shouldn't be allowed to fight if they haven't been involved in contact sport before.
"I think the training of the boxer really needs to be looked at critically, and one would wonder if three months alone is enough.
"Perhaps there is a requirement for a registered, qualified boxing coach to be doing the training, rather than having family members in the corner."
McKay was also an advocate for fighters wearing headgear.
"I believe they should wear headgear for their own safety. Perhaps it might not stop them from getting knocked out but certainly when they hit the floor heavily, at least the headgear will give them some protection and will certainly protect them against cut eyes."
However, former boxer and corporate event organiser Andrew Asher disagrees and said headgear doesn't protect you from a knock out.
"But it does obstruct your vision and make you feel safe when you are not," he said.
"The distraction of wearing headgear and the loss of vision completely outweighs any reduction of a head clash."
Asher said a mouthguard would be more effective.
"The common misconception of course is that it keeps your teeth in, the truth is it stops your jaw slamming shut at high speed – and it is this concussive impact of the bottom teeth hitting the top ones that is often the cause of a knock out."
Outspoken boxing enthusiast Sir Bob Jones also believed headgear wasn't the solution.
"That is a myth. Headgear if anything is very bad," he said.
"The reason the boxers wore headgear initially in training was to prevent them getting cuts on the eyebrow which is a really vulnerable area for cuts.
"That was translated as somehow giving them head protection or brain protection which it doesn't.
"The brain gets jolted in boxing by a punch, it doesn't matter if there is headgear in front of it. That has now been acknowledged and it serves no purpose at all other than protecting the eyebrows."
But Jones also supported the need for change around charity boxing fights.
"I am always deplored at this so-called charity boxing and I have always tried to stop it.
"Like other things, it is potentially dangerous if you don't know what you are doing," he said.
"You can't put blokes in there banging away at one another without expecting some repercussions.
"As for persuading local well-known identities to put on boxing gloves and go up against someone else when they have no idea what they are doing, and certainly the noble art of self-defence doesn't come into it, I don't like it. It is distasteful and it is dangerous."
Fight for Christchurch event promoter Callam Mitchell confirmed on Monday that a detailed review had been launched.
