Richard Huckle, 33, was reportedly stabbed to death in his cell at HMP Full Sutton using a make-shift 'shiv' crafted from a toothbrush.
Huckle was jailed in 2016 for at least 25 years behind bars for 191 child sex abuse offences against children as young as six months old.
The prime suspect for his murder is fellow prisoner Paul Fitzgerald who was jailed in 2009 for a sex-attack on a dog walker.
A spokesperson for the Ministry of Justice told the BBC: 'HMP Full Sutton prisoner Richard Huckle died on October 13.
'It would be inappropriate to comment further while a police investigation is ongoing.'
Prolific paedophile Richard Huckle was branded the 'gap year' paedophile after he admitted to 71 charges over eight years while he was living and working in Asia.
He bragged about his abhorrent behaviour in a blog in which he awarded himself 'Pedo Points' for the severity of his disgusting abuse.
Posing as a kind christian, he worked in impoverished communities teaching English and photography. He was prosecuted for crime against 23 children but police believed there could be many more victims and found over 20,000 indecent images and videos when he was arrested. Huckle had been taking the images himself and selling them for profit.
He'd even written a 60-page 'child abuse manual' which a judge described as a 'truly evil document' while passing sentencing in 2016.
Huckle's abuse was uncovered in 2014 when Australian uncovered a network of paedophiles on the 'dark' web. Sharing their findings, Huckle was arrested when he returned home to the uK to spend Christmas with his family in 2015.
As he was led away from the dock after his trial, an onlooker shouted: 'A thousand deaths is too good for you. I know one of those families. They mean nothing to you.'