Francia Marquez, a single mother and former housekeeper, will be Colombia's first Black woman vice president after a historic vote on Sunday saw the Andean country pick its first leftist president, Gustavo Petro.

Marquez and Petro won 50.4% of the vote in Sunday's election.

In front of a background emblazoned with the phrase "change is unstoppable," Marquez thanked supporters from across Colombia for assisting her and Petro's campaign in a speech broadcast from Bogota.

"After 214 years we have achieved a government of the people, a popular government, a government of people with calloused hands ... the government of the nobodies of Colombia," she said.

Colombia's new vice president-elect hails from the municipality of Suarez, a rural area of Colombia's Cauca province. Around 80% of Cauca's population lives in some form of poverty.

Marquez is a celebrated environmental activist whose opposition to gold mining in her home municipality of Suarez saw her receive the prestigious Goldman Environmental Prize in 2018 - as well as death threats from illegal armed groups.

As well as serving as Petro's vice president, Marquez is slated to lead a new equality ministry to build on her core ideas of improving women's rights and helping the poor access health and education.

Marquez actually came second to Petro in their coalition's March primary election with 783,000 votes, when she tallied more ballots than the winner of the Colombia's centrist primary.

Her political rise during the campaign follows broad demands for change and increasing concern about socio-environmental topics, Daniela Cuellar of FTI Consulting told Reuters.

"The political popularity of Francia Marquez was part of a trend in Colombia where the population is looking for a change and where socio-environmental issues are becoming more and more relevant," she said.