By james art Martin Hibbert and his daughter Eve sued Richard Hall for harassment and data protection over his claims in several videos and a book that the attack was staged.
The father and daughter suffered life-changing injuries at an Ariana Grande concert in May 2017, with Mr Hibbert left with a spinal cord injury and Miss Hibbert facing severe brain damage.
But Mr Hall argued that his actions – including an incident of filming Miss Hibbert outside her home – were in the public interest as a journalist and that “millions of people bought into the lie” about the attack.
He told a London court in a three-and-a-half-day trial in July: “The initial evidence is that there was no bomb in that room that went off.”
In a 63-page ruling on Wednesday, Ms Justice Stein said the Hibberts had won their harassment claim, but said she would not rule on the data protection claim at this stage.
The judge said there was “powerful evidence that Mr Hall’s conduct caused Mr Hibbert distress, stress and anxiety”.
Salman Abedi killed 22 people and injured hundreds when he detonated the homemade backpack bomb in a crowd of concertgoers, with the court saying the Hibberts were among those standing closest to him at the time of the blast.
Mr Hall claimed several of the dead lived abroad or were dead before the attack, telling the court he believed no one was “really injured” in the bombing.
But Jonathan Price, for the Hibbert family, said the bomb had changed Mr Hibbert’s life “in every possible way”.
“They both suffered life-changing injuries from which they will never recover,” the lawyer said.
The court heard Mr Hibbert suffered 22 shrapnel wounds and Miss Hibbert suffered a “catastrophic brain injury” after a blast from the bomb hit her in the head – leading to her presumed dead at the scene.
Mr Price added: “Martin, paralyzed, saw Eve lying next to him with a hole in her head and assumed he was watching her die, unable to help. He saw others lying dead or wounded around him.