Winston Silcott, who was wrongly convicted of the murder of Pc Keith Blakelock, will be released from prison next week.
In 1991 Winston Silcott was cleared of murdering Pc Blakelock
Silcott is serving a life sentence for the 1984 murder of 24-year-old boxer Anthony Smith.
In June last year the Prison Service moved him to an open prison in readiness for his possible release.
On Wednesday ministers backed the Parole Board's verdict that he poses no risk to the public, his solicitors said.
The former wife of Pc Blakelock has said that she believes his killers would still be brought to justice.
Silcott was convicted of murdering Pc Blakelock during the Broadwater Farm riots in Tottenham, north London, in 1985.
But six years later he was cleared by the Court of Appeal as the conviction was seen as unsafe because of tainted police evidence.
Silcott's solicitors, Bindman and Partners, have said he "remains intent on proving his innocence" of the murder of Mr Smith.
He stabbed him to death in a fight at a party in east London, but Silcott has always claimed he was acting in self-defence.
In a statement, the 43-year-old said: "I am looking forward to returning to my family and to overturning my conviction."
His solicitor Tony Murphy said: "Winston has been a model prisoner, despite a deep sense of injustice.
'Sense of injustice'
"He has spent numerous periods of leave in the community without incident.
"The real question has always been the safety of the Smith conviction, not least as it coincided with his wrongful conviction on the Blakelock case."
Pc Blakelock was hacked to death by a mob on 6 October, 1985.
On his release, Silcott is expected to return to the Tottenham area, where it is believed he has already put his name down for a course in sound engineering and computers at a local college.
Since July 2002, he has been at Blantyre House open prison in Kent.
Silcott has served nearly four years more than his original 14-year sentence tariff, according to Mr Murphy.
Pc Blakelock's former wife, Mrs Elizabeth Johnson, 52, remarried after the tragedy.
On Wednesday she said she believed the people responsible for the policeman's death would be brought to justice and punished.
"They have deprived a family of a father and a grandfather," she said.
"It never leaves you and it never goes away, you just get better at handling the situation.
"People cannot get away with murdering people and I believe that life should mean life."