Mark Stephen Murphy, 60, murdered Gregory James Thurlow in north Brisbane on October 2, 1996.
After escaping punishment for more than 25 years, as Murphy married and fathered three young daughters, "justice has eventually been done" in the Brisbane Supreme Court.
Murphy sobbed quietly in the dock while waiting to learn his fate on Wednesday - wiping tears on his T-shirt and refusing to glance at a packed public gallery.
He wept openly as he pleaded guilty on the single charge of murder.
Mr Thurlow was 27 when he vanished.
He was last seen alive leaving a Bray Park home in a green 1980 VC Holden Commodore sedan with Murphy on October 1, 1996.
Mr Thurlow was never seen alive again.
The night before, Mr Thurlow had been picked up by police and spent the night in the Brisbane watchhouse.
Murphy was livid with his housemate, later telling police Mr Thurlow was a nuisance who brought unnecessary attention to the house.
The pair were drinking and injected drugs at a friend's house when Murphy's rage erupted as they drive home and he decided his flatmate had to die.
"He (Murphy) described Thurlow as a petty criminal ... he was disruptive, selfish, loud and obnoxious," prosecutor Todd Fuller told the court.
"He told police that he started contemplating Mr Thurlow's behaviour ... and perhaps he was going to kill him."
He grabbed a hammer hidden under the car seat and hit Mr Thurlow once in the side of the head.
Dazed, Mr Thurlow leapt from the car and tried to escape on foot through a paddock, only to be snared in a barbed-wire fence.
Murphy soon caught up to his housemate and smashed him a second time in the forehead knocking him unconscious.
He stuffed Mr Thurlow's body in the car's boot before he later heard moaning coming from the trunk.
"He then struck him one further blow to the head ... in his description to finish him off leaving him silent and covered in blood."
Murphy went to his partner's house to wrap the body in plastic, clean the car, and dispose of the weapon and clothing.
Mr Thurlow's body remained in the boot of the car for "two or three days" before Murphy drove to a state forest near Inskip Point north of Brisbane to dispose of the body.
"He said a few words over Mr Thurlow's body before he buried him," Mr Fuller said.
Murphy was always a suspect in Mr Thurlow's disappearance before he was finally arrested in 2020 by cold case investigators.
After more than two decades of denials, Murphy finally confessed and apologised to the Thurlow family.
"Mr Murphy is deeply remorseful," his lawyer told the court.
"His actions have caused them endless grief and pain, and he understands that nothing he says can ease their suffering."
Justice Peter Applegarth accepted Murphy's deep regret before sentencing Murphy to life in prison.
"Justice has eventually been done," Justice Applegarth said.
"Your actions have had a devastating effect on Mr Thurlow's family, both living and head.
"His parents died hoping that he might somehow miraculously appear again in their lives."