Daman Sehra and his uncle Derek Brennan killed 32-year-old Amjad Khan last year and were convicted of his murder last week.
Both men were today sentenced at Wolverhampton Crown Court, where Judge Michael Chambers QC jailed Sehra for 20 years and Brennan for 18 years.
Mr Khan died in hospital five days after he was attacked by the two men at a flat in Oldbury in the early hours of June 8 last year.
The flat in Yardley Close, Bristnall Fields, belonged to Sehra's mother Lisa, who is also Brennan's sister.
Mr Khan arrived at the flat at 12.41am to meet Lisa Sehra but within minutes of being let in he was beaten, kicked and stamped on and left with serious head injuries which would prove fatal.
Lisa Sehra called 999 while her two relatives were still attacking Mr Khan and the two men then escaped out of the window when emergency services arrived.
The defendants, who stopped at Asda in Oldbury to buy alcohol in the aftermath of the attack, said Mr Khan had been "forcing" crack cocaine and heroin onto Ms Sehra, claims that the judge dismissed at sentencing.
Judge Chambers said: "This case involved what in my judgement was an appalling, unprovoked, gratuitous assault.
"The 999 call which was made while you were still attacking Amjad Khan lying defenceless on the ground is a chilling representation of what you both did and will certainly remain with me for some time.
"This was a brutal sustained attack involving kicking and stamping on the deceased's head causing fatal injuries.
"You arrived at 12.05. Coincidentally Lisa Sehra was expecting the arrival of a friend. I'm quite satisfied the reason he was there was solely of friendship not to supply drugs and not to supply drugs in return for sexual favours as was alleged.
"Lisa Sehra tried to intervene but you ignored that so she felt all she could do was ring 999.
"I do not accept that Derek Brennan put him in the recovery position before you left. The two of you robbed him of his Armani bag.
"I'm not persuaded either of you have any real remorse."
Sehra, 23, had admitted manslaughter on the ground of diminished responsibility but denied murder, claiming it was never his intention to kill or harm Mr Khan.
Brennan, 33, denied both murder and manslaughter but both men were found guilty of murder by jurors in Wolverhampton.
Mr Andrew Smith, prosecuting, said: "Both men were under the influence of drink and Sehra was under the influence of drugs.
"Both defendants have extensive previous convictions."
In a victim statement, read by Mr Smith, Mr Khan's sister, Hina Khan, said: "The family have been robbed of their piece of mind and sense of security.
"I want those responsible to see our pain and to hear our heartache.
"He is someone we miss far more than words can ever express.
"His absence from family life will be felt continually."
Both defendants had also been charged with attacking a 15-year-old boy at a different address in Oldbury earlier the same night.
Sehra, of no fixed address, was found guilty of attempting to cause grievous bodily harm regarding that attack and had previously admitted a charge of assault by actual bodily harm.
Brennan, of Halesowen Road, Netherton, was found not guilty of attempting to cause grievous bodily harm and not guilty of assault by actual bodily harm regarding the attack on the teenager.
Meanwhile Sehra had also previously pleaded guilty to burglary, affray, threatening another with a blade, assaulting an emergency worker and criminal damage regarding a third incident which took place on November 11, 2018.
Mr Smith said Sehra and others burst into a hotel room in Dudley that night at 3.30am and "squared up" to strangers who had been sleeping inside, the group left with one of the iPhones from inside the room.
Later that day Sehra went to a nearby McDonald's where he was talking in a "hostile way" before leaving, then returning with a knife, Mr Smith said.
He added that police were called and found the knife in a nearby hedge and the stolen iPhone.
Sehra was taken into police custody in Oldbury where he threatened officers, spat blood at one then damaged the cell by smearing blood on it.
He was given five years for attempting to cause grievous bodily harm, 27 months for burglary, 18 months for affray, nine months for threatening another with a blade, six months for assaulting an emergency worker and three months for criminal damage, all of which will run concurrently.
Ms Caroline Haughey, defending Sehra, said: "Mr Sehra has asked me to reiterate his shame and remorse for his behaviour.
"He said no matter what someone has done, nobody deserves what happened.
"His life was littered with crime and a lack of opportunity and abandonment."
Mr Balraj Bhatia, defending Brennan, said there was a lack of intent to kill and a lack of premeditation.
He added: "This was a time when he was extremely drunk, when he sobered up the following day and recognised the severity of what happened that's when the remorse kicked in."
Both men have already spent 497 days on remand which will be deducted from their jail terms.