Jon Venables, now 29, was originally imprisoned for life along with 10-year-old friend Robert Thompson for the 1993 murder of toddler James Bulger in Liverpool.
The pair were released on licence in 2001 and given secret new identities for their own safety, but Venables returned to jail in July 2010 after pleading guilty to three charges in relation to child pornography.
A parole board statement released Thursday said: "We've had confirmation that all parties have been told and we can confirm that it was a release decision. He will be released."
The boy's father Ralph said he was "disappointed and dismayed" by the news.
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"For Ralph and his family the living nightmare continues and is exacerbated by the problems now created by the reckless decision to free Jon Venables without any publicly disclosed safeguards," said his solicitor Robin Makin.
"Jon Venables is a sex offender who has murdered once and made it clear when posing as the mother of a child that an 'ultimate thrill' for him was the sexual abuse of a child.
Venables admitted downloading 57 pornographic pictures of children on to his computer and distributing indecent photos of children.
The sadistic torture and murder of Bulger caused horror across Britain and fears about attacks on the two killers continue.
Bulger was snatched from a shopping centre before being beaten with bricks and iron bars and dumped on a railway line.