Rousseff garnered 51.62 percent of the votes, while conservative opposition candidate Aecio Neves of the Social Democratic party (PSDB) got 48.38 percent, with 99.77 percent of the votes counted, the country's Supreme Electoral Court (TSE) said.

Rousseff, 66, won what was considered as Brazil's most bitterly contested presidential race in two decades, as an economic slowdown gave the pro-business PSDB an opportunity to make headway in its campaign.

Brazil reelects president Rousseff to second termAcknowledging the economic troubles, Rousseff's campaign promised "a new cycle of development (that will be) more productive and more competitive" for Latin America's biggest economy.

Her win means another four years in power for the Workers' Party, which has held power for 12 years and leveraged an economic growth to expand social welfare programs and lift more than 40 million people from poverty in Latin America's most populous country.

In 2002, her predecessor Luiz Inacio Lula da Silva defeated the PSDB's Jose Serra to win his first term, and in 2006 he beat the party's Geraldo Alckmin, current governor of Sao Paulo state, to win his second term.