"My mission is to eradicate poverty," Dilma Rousseff said after the country's Supreme Electoral Tribunal declared her the winner in Sunday's runoff election.

As the nation's first woman to hold the office, Rousseff said she has a mission to fight for more gender equality in Brazil.

"I hope the fathers and mothers of little girls will look at them and say yes, women can."

Rousseff -- President Luiz Inacio da Silva's right-hand woman -- has served as his chief of staff.

Previously, as energy minister, she claims to have helped turn Brazil into one of the world's leading energy giants.

Millions of voters lined up across Brazil's vast territory to vote in the heated runoff.

In 60 Brazilian cities, voters used their thumbs instead of ballots on a newly launched biometric system, where voters scan their fingers to log in and vote.