Boric garnered 56% of the vote compared to 44% for his opponent, right-wing populist Jose Antonio Kast.
"I am going to be the president of all Chileans," Boric said in a brief televised video conference call with outgoing President Sebastian Pinera. "I will not rule alone within four walls", Anadolu Agency reported.
"We all hope you have a good government," Pinera replied after inviting Boric to a meeting on Monday, which the newly elected president quickly agreed to.
Kast, who finished on top in the first round of the elections held on Nov. 21, acknowledged the victory of the former student leader.
“I have spoken with Gabriel Boric and congratulated him on his great triumph. As of today, he is the president of Chile and deserves all our respect and constructive collaboration. Chile always comes first," he wrote on his Twitter account.
Boric, a progressive lawmaker, played an important role in the 2011 student protests against structural inequality in Chile. He has promised to address the country´s inequality by reforming Chile's pension and health care systems and reducing the work week from 45 to 40 hours.
The member of the left-wing “I approve Dignity” coalition finished second in the first round with 26% of the vote, although he has won almost every poll since then.
While Boric competed for a Chile where social rights and freedoms are protected, Kast promised "order and progress" to the Chilean people.
Kast, a 55-year-old lawyer and former deputy, showed his sympathy for the dictatorship of Augusto Pinochet. He is said to resemble former US President Donald Trump and Brazilian head of state Jair Bolsonaro in his anti-immigration stance and anti-abortion rhetoric.
Since the November election, both candidates had moderated their speeches in an effort to win the votes of a wider electorate
More than 8.3 million Chileans participated in the elections, or close to 55% of those eligible to vote, the highest number since voting became voluntary in the South American country in 2012.
Boric's election marks an important victory for Latin America's left, which has returned to govern in some countries of the region.
Left-wing leaders greeted the new Chilean president.
”Congratulations on your victory, my dear friend Gabriel Boric!” Peruvian President Pedro Castillo wrote in his Twitter account.
“The victory you have achieved is that of the Chilean people and we share it with the Latin American people, who want to live in freedom, peace, justice and dignity! Let’s continue to strive for the unity of our nations,” he said.
Bolivian former President Evo Morales joined him in saluting "the democratic vocation of the Chilean people,” and Luiz Inacio Lula Da Silva, Brazil's former president, rejoiced over “another victory of a democratic and progressive candidate in our Latin America.”