De Morgen newspaper said Frank Van Den Bleeken, who has spent the past 30 years in jail for repeated rape convictions and a rape murder, will be euthanised in prison in the northwestern city of Bruges.
"Euthanasia will indeed be implemented," a justice ministry spokeswoman told the Flemish-language newspaper, which gave the date as January 11. "Now the time has come."
Van Den Bleeken had for years requested that the state help him end his life due to what his lawyer Jos Vander Velpen called "unbearable" psychological suffering.
He received the all-clear last September.
Belgium legalised euthanasia in 2002, the second country in the world to do so after The Netherlands, and logged a record 1,807 cases of euthanasia in 2013.
Its strict conditions for a mercy killing include that patients must be capable, conscious and have presented a "voluntary, considered and repeated" request to die.
Van Den Bleeken, considering himself a menace to society, had refused to be considered for early parole, but found the conditions of his detention inhumane, according to an interview he gave Belgian media.
Neither the prisoner's lawyer nor a spokesperson for the justice ministry could be reached by AFP for comment on the De Morgen report which was also carried by the Belga news agency.
Even someone as evil as he should be shown 'a better way'. Die to your 'self' and live for Jesus Christ! If he only knew how powerful and transforming God can be.