Chileans elected former student leader Gabriel Boric as the country's new president on Sunday.
The 35-year-old was facing right-wing politician Jose Antonio Kast in a run-off vote for the country's highest office.
With 99% of the vote counted, Boric received 55.9% of the vote, while Kast took 44.1%.
Kast said on Twitter he had spoken to his rival and congratulated him on "his great triumph."
"From today he is the elected President of Chile," Kast wrote on the social media site.
A total of around 15 million people are eligible to vote in the South American country.
Boric has promised public education, better health care and champions the rights of migrants, indigenous people and homosexuals.
A devout Catholic
Kast - father of nine children and a devout Catholic - promised tax cuts, a border wall against illegal immigration and a firm hand against criminals. He is considered a sympathizer of former dictator Augusto Pinochet.
During the election campaign he said: "If Pinochet were still alive, he would vote for me."
For a long time, Chile was considered a shining example in a region marked by poverty, violence and political unrest. The country with more than 19 million inhabitants has the highest per capita income in South America. Poverty has been significantly reduced in recent decades.
But Chile also suffers from growing social inequality. Large parts of the health and education systems have been privatized, and more and more people feel left behind.
Two years ago, thousands took to the streets every day for weeks to demand social reforms and the resignation of President Sebastian Pinera.
