With 99.2 percent of the ballots counted, Maduro defeated his opposition challenger Henrique Capriles, who gained 49.07 percent of the votes, reported Xinhua.
The turnout of Sunday's vote was 78.71 percent, according to Lucena.
Maduro, candidate from the ruling United Socialist Party, will complete the remaining time of the six-year term left by late president Hugo Chavez starting from January.
The results surprised many as opinion polls before the vote had gave Maduro a nearly 10-point lead over Capriles from the opposition Democratic Unity Roundtable coalition.