Far-right candidate Jose Antonio Kast concedes defeat to leftist rival Gabriel Boric in the Andean nation's election.
Gabriel Boric, a leftist millennial who rose to prominence during anti-government protests has been elected Chile's next president after a bruising campaign against a free-market firebrand likened to Donald Trump.
With 68 percent of 46,887 polling stations reporting on Sunday, Boric had 55 percent of the votes, compared to 45 percent for his opponent, lawmaker Jose Antonio Kast.
Kast recognised defeat and called his opponent to congratulate him on his "grand triumph" as supporters of Boric gathered in downtown Santiago to celebrate.
'No to Dominga'
"I am going to be a president of all Chileans, whether you voted for me or not," Boric, 35, said in a call with current President Sebastian Pinera on Sunday night. "I am going to do my best to get on top of this tremendous challenge."
During a speech after his electoral victory, Boric said he will oppose mining initiatives that "destroy" the natural environment, including the controversial $2.5 billion Dominga iron, copper and gold mining project.
He said his government will also expand social rights but will do so with fiscal responsibility and taking care of the economy in the world's top copper producing nation.
"Destroying the world is destroying ourselves. We do not want more 'sacrifice zones', we do not want projects that destroy our country, that destroy communities and we exemplify this in a case that has been symbolic: No to Dominga," he said.
Boric breaks precedent
Kast, who has a history of defending Chile's past military dictatorship, finished ahead in the first round of voting last month but failed to secure a majority of votes.
That set up a head-to-head runoff against Boric, who finished two points behind.
Boric broke a precedent.
Since the return of democracy three decades ago, no candidate leading after the first round has ever been defeated in the runoff.
But no president has ever been elected without winning in the capital, Santiago, which Boric carried comfortably in the first round.
Kast, 55, a Roman Catholic and father of nine, emerged from the far right fringe after having won less than 8 percent of the vote in 2017.
He rose steadily in the polls this time with a divisive discourse emphasising conservative family values and playing on Chileans' fears that a surge in migration — from Haiti and Venezuela — is driving crime.
A longtime lawmaker, he has a record of advocating more restrictive abortion laws.
He also accused outgoing President Sebastian Pinera, a fellow conservative, of betraying the economic legacy of General Augusto Pinochet, the country's former military leader. Kast's brother, Miguel, was one of Pinochet's top advisers.
Boric's election pledges
Boric, 35, has become Chile's youngest modern president.
He was among several activists elected to Congress in 2014 after leading protests for higher quality education.
If elected, he said, he will "bury" the neoliberal economic model left by Pinochet and raise taxes on the "super rich" to expand social services, fight inequality and boost protections of the environment.
In recent days, both candidates tried to veer toward the centre.