David Bain has been found not guilty of the 1994 murders of five of his family members.
The jury reached their verdict after five hours and 50 minutes of deliberations.
Some of the jury were in tears as the verdicts were read to a packed courtoom.
"You may leave the dock Mr Bain," Justice Graham Panckhurst told David Bain.
Loud clapping and cheering came from the gallery as each of the five "not guilty" verdicts were read out.
After the verdict was read, David Bain's long-time supporter Joe Karam raised his thumbs to supporters.
He said: "Never in doubt, never in doubt.
"I thank you all."
There were tears on the faces of the Karam family as the news sank in.
They and supporters rose to the give the jury a standing ovation as they filed out.
Mr Karam told supporters that a highly emotional Bain was taking five minutes to compose himself before speaking to supporters and an assembled media throng.
Richard Karam, Joe's son, said: "The supporters were all very much in shock. They had expected the verdict but then they had been expecting this for the nine years they had known David."
He said it was a shame it had taken so long.
"There will be a couple of shandies consumed I'm sure."
The jury alerted the judge at 4.25pm they had reached a verdict.
Inside High Court number one in Christchurch, all public gallery seats were taken as Bain family members and supporters sat waiting for the jury to come back.
After the verdicts were read out, five men and seven women of the jury were thanked by Justice Panckhurst and excused from jury service for 10 years.
Bain, 37, faced a retrial for the murders of his parents and three siblings at their Dunedin home on June 20, 1994, after the Privy Council in 2007 quashed his 1995 convictions for their deaths.
The Law Lords in 2007 had ruled Bain had been the victim of a "substantial miscarriage of justice".
By the time their decision saw him freed on bail in May 2007, Bain had served more than 12 years of a minimum 16-year jail term. He and his supporters had always maintained his innocence.
Justice Graham Panckhurst sent jurors out to consider their verdict on Thursday evening at the Christchurch High Court retrial.
The 12 jurors had heard from 184 witnesses over 54 days of evidence in what Bain's lawyers have described as "undoubtedly the most extraordinary case in New Zealand's history".
Today, as they filed out of court after delivering their verdict, Bain supporters yelled out "Well done, well done" and one juror replied that he needed a drink.
Bain's defence team argued his father, Robin, murdered his family before turning the gun on himself.
However, the Crown alleged he murdered his father Robin, mother Margaret, two sisters Arawa, 19, and Laniet, 18, and brother Stephen, 14, and used his paper run as an alibi before putting his bloodied clothes in the washing machine and calling police.
Expert evidence focused on whether Robin could physically have shot himself, the age of fingerprints on the rifle, length of bloodied footprints and the timing of David Bain's paper round and a message left on the family computer.
The defence argued the Robin Bain was depressed about his marriage and in an incestuous relationship with his prostitute daughter Laniet, while prosecutors painted Robin as a gentle man and Laniet's claims as unreliable.
Summing up for the defence on Wednesday, Michael Reed QC said Robin Bain had a bite mark, a bruise on his hand that was less than 12 hours old, and what one witness described as the appearance of blood under his fingernails.
But Mr Reed said there was very little blood on Bain, which showed he checked on his family members but did not shoot them.
He spoke of Robin Bain having a history of depression and being worried about his daughter Laniet - who was going to "blow the whistle" on an incestuous affair - and a marriage that was all but over.
"Who is the more likely person to be a homicidal maniac? Is it the nice friendly, jovial 22 year-old with a new girlfriend and dog, enjoying what he is doing ... Or is it this sad, sad father who is going downhill?"
Mr Reed said, "The tragedy for David is that David still loves his father. He's not the father that David knew all those years. He's a man that suddenly flipped."
Summing up on Tuesday, Crown prosecutor Kieran Raftery told the jury that they should focus on who killed Stephen Bain, as the same person killed Margaret, Arawa, Laniet and Robin Bain.
He said the blood found in Stephen Bain's room and the fact that he was strangled pointed to a violent struggle.
He said the defence had described Robin as 58 going on 78 and, therefore, Robin was not the man who fought with Stephen.
He showed the jury how he believed David and Stephen's hands had come into contact with the rifle during the struggle. Mr Raftery told the jury that small samples of Stephen's blood were found on Bain's clothing.
Mr Raftery also told the jury that Bain did not act like a brother when he heard Laniet making gurgling sounds after returning from his paper round, waiting 20 minutes before calling 111.