He was jailed for 32 years with a non-parole period of 23 years. With time already served behind bars, he is first eligible for release in October 2039, news.com.au reports.
The 23-year-old victim was shot seven times with a .22 calibre handgun, including through his eye, brain and heart.
His body was found slumped on the blood-spattered tiled entrance of the house he was staying in with car keys still in his hand.
"The offender lay in wait in the victim's front yard in darkness behind a tree until the victim arrived," the judge said.
"The offender did not confront the victim to argue with him or to threaten him.
"Rather, as the victim entered the front door of the house, unaware of the presence of the offender, the offender stepped forward and executed him with six gunshot wounds to the head and one to the chest.
"The offender departed immediately, being fully aware that the victim was dead."
Medical evidence before the killer's trial revealed each shot was capable of being fatal on its own.
The victim's uncle and murderer, who appeared in Sydney today via video link from jail, paced back and forth in his prison green jumper and shorts throughout his hour-long sentencing.
He sighed repeatedly, scratched his head and long beard, and at one stage bent his knee to put his foot up on the table.
When the jury returned its verdict earlier this year, he spat at them and called them "pigs".
The younger man had travelled to Sydney from overseas to live with his aunt, uncle and their daughter – who had been supposed to "take part in an arranged marriage with the victim".
Justice Johnson said the young man's family, in their victim impact statements tendered in court, spoke of his great hopes and expectations when he came to Australia in January 2015.
"With those expectations being dashed by his murder just three months later," the judge said.
By late February 2015, following an argument with his uncle, which saw him kicked out of their house, the victim was living at another property several kilometres away.
"She [his aunt] would visit the victim at that house from time to time," Justice Johnson said.
"The evidence revealed by that time, there were signs of affection between the offender's wife and the victim."
At trial, crown prosecutor Richard Herps said the killer had bought five tracking devices from Spy City and multiple sim cards in the weeks before the murder to monitor the pair's location, as well as their vehicles.
He said the aunt found one of the A$500 devices in her car and destroyed it.
"We say that the accused has actually logged into this account 609 times in four weeks in order to discover the location," the prosecutor said.
In the fortnight before the death, the killer sent a "large number" of strongly-worded text messages to his wife and nephew, some of which had highly sexual content.
The married couple slept in separate bedrooms, the court heard.
The judge today said some of those messages "convey the tone and content of the offender's thought processes".
He said they revealed the man's firm belief that they "were engaged in a sexual relationship".
On April 15, 2015, the man sent a text to his wife that said: "I cannot take it any more and I fear I will get carried away."
One week later, he said: "I am devastated and stepped over and I shall regain my dignity".
The man sent messages to his wife on the night of the killing, including a text at 8.59pm reading: "God will punish you."
The prosecution alleged at trial that the nephew spent hours in an intimate "meeting" with his aunt.
The aunt's DNA was also allegedly found on swabs of the victim's genitalia, palm and wrist.
Justice Johnson said today he was satisfied the pair "rendezvoused" at a location in southwest Sydney that evening.
The pair parted ways but the victim had a seven-minute phone call with his aunt from his vehicle before he returned home and was gunned down.
"Forensic evidence adduced at the trial confirmed the existence of a sexual relationship between the victim and the offender's wife," he said.
"I am satisfied that the offender's motive for killing the victim related to his outrage at the relationship which had developed (and continued) between the victim and the offender's wife, and the sense of dishonour which the Offender felt in that respect for cultural reasons."
The man has shown no remorse for the "grave crime".
"The offender is literally in a continuing state of denial with respect to this offence," the judge said.
