Ryan Herbert was aged 16 when he was jailed for life in 2008 for murdering Sophie Lancaster in a park in Bacup, Lancashire.
The Parole Board decided Herbert can be released on licence, 15 years after he took part in the attack.
Sophie’s mother Sylvia Lancaster, who launched a foundation in her memory to stand against violence and prejudice, told the PA news agency: “The reality is obviously it’s never going to be enough.
“He had to come out some time and unfortunately it doesn’t seem long enough but that’s the reality of the situation and you’ve got to deal with it.
“I don’t want to waste any more time thinking about him now… Hopefully I can forget about him.”
Herbert was handed a life sentence after admitting murdering the 20-year-old, who died from her injuries after being viciously beaten as she cradled Robert Maltby’s head in her lap in 2007.
He also pleaded guilty to assault causing grievous bodily harm with intent to Mr Maltby and was given a minimum term of 16 years and three months - later reduced to 15-and-a-half years on appeal.
In 2020, Herbert, of Bacup, Lancashire, had his tariff cut to 14-and-a-half years when a High Court judge concluded he had made “exceptional progress” in jail.
The Parole Board found he had made “significant changes to his life which reflected his remorse, his insight and increased maturity”.
Brendan Harris, who was found guilty of Miss Lancaster’s murder in 2008 and admitted the attack on Mr Maltby, was jailed for life with a minimum term of 18 years.
He, Herbert and four other teenage boys “savagely and mercilessly attacked” Mr Maltby in Stubbylee Park, Bacup, during the early hours of August 11, 2007.
Gap-year student Miss Lancaster rushed to help her boyfriend as he lay unconscious and shouted at his attackers to leave him alone.
Herbert and Harris then turned on her, subjecting her to a “sustained and vicious attack” which involved her head being kicked and stamped on.
Miss Lancaster never regained consciousness and died in hospital 14 days later.
It appeared the couple were attacked because they looked and dressed differently and Herbert later told people there were “two moshers nearly dead” in the park, according to court hearings.
At the time of his crimes Herbert had an “anti-social lifestyle” and spent time with “negative friends” who he had a “misguided sense of loyalty” towards, drank and took drugs, the parole papers said.
Herbert’s behaviour behind bars had “initially been poor” but this changed once he moved into an adult prison and he had taken part in rehabilitation programmes.
After being moved into an open prison in November 2020, he “improved his education with studies to degree level” and had “fully engaged with resettlement activities”.
He had a job and there was “positive feedback about his work”.
The document added: “No concerns about compliance had been identified and Mr Herbert had good working relationships with professional staff.”
Witnesses, including his probation officer, recommended he be released on licence.
Herbert, who became eligible for release in February, will be subject to restrictions on his movements, where he lives and who he contacts.