Almost half of the more than 1.7 million people who voted in an online poll chose Fuleco ahead of 'Zuzeco' and 'Amijubi'.
The mascot is a three-banded armadillo, which is an endangered species in Brazil.
The tradition of a World Cup mascot dates back to 1966, when a lion named 'World Cup Willie' was chosen for the tournament in England.
Since then, the mascots have ranged from two German boys ‘Tip and Tap’ in 1974, to ‘Pique’ the chili pepper in Mexico in 1986, and ‘Zakumi’ the leopard, who represented the tournament in South Africa in 2010.
The yellow and blue armadillo was chosen in September and huge inflatable versions were set up in Brazil's 12 host cities. However, authorities were forced to take them down or increase security in at least three cities after vandals attacked them.
Fuleco is expected to make an appearance in Sao Paulo this week at the draw for the 2013 Confederations Cup. The draw for the World Cup warm-up competition takes place next Saturday.
The naming of the mascot came on the same day that FIFA unveiled the posters to be used to publicise the tournament. Each of the 12 host cities has its own poster.