Mrs Justice King analysed issues in the family home in 2014 following Ellie's death and concluded that Butler was 'responsible for Ellie's death' - two years before he was found guilty by a jury.
Butler was tried for murder in a criminal court, where the standard of proof is higher, and also found guilty of Ellie's murder.
After a series of appeals and attempts to keep the family court judgement secret, a redacted form of the ruling was finally released today.
It sets out the horrific conditions of domestic violence in the Butler home in Sutton, south London in the run-up to Ellie's shocking murder.
Speaking of the parents' relationship, Mrs Justice King stated: 'The picture is one of violence and abuse coupled with a regular excess of drink and or drugs.'
The judge's ruling also serves as another indictment of the decision of Mrs Justice Hogg, the family judge who decided to hand Ellie back to Butler and his partner Jennie Gray less than a year before the murder.
Mrs Justice King found: 'When they gave evidence to Mrs Justice Hogg, the parents had been unclear about their future as a couple, their relationship was not settled and at the time they had no suitable accommodation in which to live with the children.'
She said Mrs Justice Hogg's ruling tore Ellie from her grandparents, who has been her 'psychological parents' since she was removed from Butler's care as a baby.
Ellie's grandfather Neal Gray had warned family court judge Mrs Justice Hogg she would have 'blood on your hands' after she handed the six-year-old back to her parents in November 2012.
A High Court judge had refused to allow publication of the ruling over fears it could prejudice a potential retrial if Butler mounted a successful appeal.
But three court of appeal judges today ruled the judgement, which found Butler responsible for Ellie's killing, could be reported.
They found the High Court judge 'made the wrong decision' to keep it secret after making 'no assessment of the likelihood of a retrial' and said the risk of prejudice was 'so negligible that it should have been given little or no weight'.
It can now be revealed Mrs Justice King said she was 'satisfied so that I am sure that Ellie died as a result of being hit over the head with the leg from a child's table or pushed with some force'.
Mrs Justice King said she was satisfied that Ellie was 'routinely smacked' and was 'subjected to serious emotional abuse and her sibling suffered 'serious emotional harm'.
The judge criticised Gray for her 'wholesale failure to protect the children' describing Ellie's younger sibling as 'deeply traumatised'.
Heart-breaking notes kept in a diary associated with Ellie's sibling revealed the depth of the damage done.
Ellie's sibling said the house was a 'bad house' and told how both children were 'smacked lots of times'.
The entries revealed 'dad hits mum and makes her cry' and that Ellie's younger sibling's view of itself as 'bad'.
Shockingly, when the child had wet itself or defecated in its pants Butler would put its head down the toilet and flush as punishment.
In a damning indictment, the judge found Gray had 'walked away' from her living child.
Mrs Justice King said: 'With the benefit of hindsight, however, there were some other more sinister matters of concern such as the mother attending at hospital on occasions with a number of lacerations, made more chilling by a Google search found on her computer 'stabbed in the leg...' and another Google search dated September 2008 refers to 'Treatment of Broken Noses'.'
The judgement also detailed how maternal grandfather Neal Gray had last seen Ellie at McDonald's in Sutton the day before her murder.
In a statement to police, he said his two grandchildren looked like 'they had been dragged through a hedge' and his daughter looked as if 'she had lost it'.
As he said his final goodbye, Ellie said she loves her grandparents and misses them.
