The 52-year-old suffered severe brain trauma in the attack at HMP Frankland, Durham, on February 26.
A Ministry of Justice spokesperson said: “The murders of Holly Wells and Jessica Chapman remains one of the most shocking and devastating cases in our nation’s history, and our thoughts are with their families.”
Huntley, who murdered the 10-year-olds in 2002, had been on life support in hospital after being hit repeatedly over the head by an inmate armed with a metal bar.
His life support was switched off at lunchtime on Friday after brain tests showed he was in a vegetative state, The Sun reported, and he was confirmed dead on Saturday.
The attack left Huntley blind, the newspaper said, and it quoted a source saying: “Huntley never recovered from the battering and never stood much of a chance of doing so.”
Murderer and rapist Anthony Russell, 43, reportedly shouted “I’ve done it, I’ve done it” after Huntley was attacked in the recycling area of the prison.
Ian Huntley murdered Holly Wells, left, and Jessica Chapman
Ian Huntley. Photo: Toby Melville/PA
News in 90 seconds – Saturday, March 7
Durham Constabulary has not identified the suspect but it said on the day of the attack that a man in his mid-40s had been detained.
After the attack, Huntley’s only daughter Samantha Bryan, 27, told The Sun on Sunday of her father: “There’s a special place in hell waiting for him.”
Huntley murdered Holly and Jessica after they left a family barbecue to buy sweets in Soham, Cambridgeshire, on August 4 2002. He dumped their bodies in a ditch.
Russell was sentenced to a whole-life tariff in 2021 for the murders of Julie Williams, 58, and her son David Williams, 32, at separate flats in Coventry, and pregnant 31-year-old Nicole McGregor, who was found in woodland near Leamington Spa three days later.
Russell also raped Ms McGregor.
Huntley’s life sentence recommended he serve at least 40 years for the Soham murders.