Three other men have been jailed for between seven and 15 years.
Daniel Zamudio, 24, was beaten unconscious, burned with cigarettes and had swastikas carved into his skin. He died of his injuries three weeks later.
The crime shocked the country and prompted legislators to approve a bill against homophobic crimes.
But correspondents say a similar assault in recent days has led to calls for tougher action.
A week ago, a 21-year-old gay man was beaten up in a provincial town 60km (37 miles) south of Santiago and is still fighting for his life, the BBC's Gideon Long reports from the Chilean capital.
Activists say the man has had one of his eyes cut out with a knife by the attackers.
Mr Zamudio's family and friends clapped as the four sentences were read out at a court in Santiago on Monday, but his mother later said she thought some of the sentences were too lenient.
"I just want them to rot in prison for what they did. Let them dry up behind bars," Jacqueline Veras told the Associated Press.
Patricio Ahumada Garay was sentenced to life in prison by the a panel of three judges.
Two of his accomplices, Alejandro Angulo Tapia and Raul Lopez Fuentes, were given 15-year sentences.
The youngest of the group, Fabian Mora Mora, was jailed for seven years because he co-operated with investigators and had no previous convictions.
After the four men were found guilty last week, Judge Juan Carlos Urrutia said they had shown "total disregard for human life".
Daniel Zamudio was attacked on the night of 2 March 2012 at the San Borja de Alameda park.
He was left for dead after an ordeal that lasted for several hours.
The attackers broke one of his legs with a large stone, beat him with bottles, and carved swastikas into his body with broken glass before walking away.
He was unable to recover from such serious injuries and died in a hospital 25 days later.
Chile's Gay Liberation and Integration Movement told the Efe news agency that Mr Zamudio had "made history in the fight against discrimination".
"He touched the whole country about the gravity of homophobia," it said.
A man in Chile has been sentenced to life in prison for the murder of a gay man who was brutally attacked in a park in Santiago in March 2012.