Iraci Hassler will be the second woman to hold this office, which has not been headed by a communist since the end of Augusto Pinochet's dictatorship in 1990.
She was elected as a candidate in the citizen primaries convened by the Santiago's Constituent Mayoralty platform, which brought together over 50 social, political, and women's rights organizations.
Besides running against outgoing Santiago's Mayor Felipe Alessandri, Hassler faced the Party for Democracy (PPD) candidate Alfredo Morgado, the Green Ecologist Party (PEV) member Fernando Neira, the Humanist Party (PH) representative Helmuth Eberhard, and Boris Araos from the Patriotic Union (UP).
Her victory represents a historic triumph to the Communist Party, which had never had a single one of its members in Santiago mayor's office since the end of Augusto Pinochet's dictatorship in 1990. She will also become the second woman to head the post since 2012.
"We hope that what is happening today in Santiago is the prelude to what is also coming in our country, where never again will the Right govern against our neighbors," Hassler said.
"We are going to have a new Constitution and a transformation in Santiago's neighborhoods to conquer our dignity and a good living," she added.
With 100 percent of the votes counted, progressive parties concentrate the majority of the 155 seats of the Convention that will draft a new Constitution. The independents obtained 48 seats, the leftist lists totaled 52 and the right-wing ruling party Let's Go for Chile reached 38.