"Thank you my dear people!!! Viva Venezuela!!!" Chavez, who won another six-year term after almost 14 years in power, wrote on Twitter after the results were published. "Thank you God! Thank you to all of you!"
Hundreds of Chavez supporters had already started to party in front of the Miraflores presidential palace before the results were announced, playing salsa music, holding signs and setting off fireworks.
Based on 90% of the results, Lucena said Chavez won 7,444,082 votes, compared to 6,151,554 for Capriles. Turnout was a massive 80.94% of the 19 million eligible voters.
"We had a calm electoral process without incidents," she said.
The 9.45-point margin of victory is close to the 10-point lead Chavez was given in the latest opinion poll.
Other polls had put the candidates in the virtual tie, raising hopes in the once-divided opposition that they were close to defeating Chavez.