Maduro - the anointed successor of left-wing firebrand Hugo Chávez, who died in 2013 - is facing two main challengers: Henri Falcón, a former governor, and Javier Bertucci, an evangelical preacher.
Ahead of the vote, some polls showed Maduro and Falcón, who broke with Chávez in 2010, running almost neck and neck. Falcón supporters hoped for a historic upset, saying their candidate's economic plan to curb the world's highest inflation rate had struck a chord with a starving populace.
Opposition supporters struggled with whether to honour the boycott or vote.
In eastern Caracas, Maria Diaz, a 30-year-old accountant whose infant child died in a public hospital last month because of a lack of medicines, said she voted for Falcón "because I don't think you win anything by abstaining."
"Look, the country's situation, especially food and medicine, are really bad," she said. "We need change."
Amid reports of empty polling stations and light voting nationwide, Falcón urged people to go out and vote, not "stay home with arms crossed." He denounced "irregularities," including the illegal installment of registration booths for government benefits near at least 300 voting centres, a move he deemed an attempt to "buy the dignity of a sector of the population with blackmail."
"I call the electoral authorities to take steps as soon as possible because there's irregularities going on across the country, and the agreements we've signed are being violated," he said.
Bertucci also decried fraud.
"We've received reports of intimidation to voters, voters being asked who they're going to vote for and being offered money and food," he said. "This is not a democratic act ... There can't be freedom if they buy out hungry people."
Those honoring the boycott spoke of a collision of emotions - anger at the Government, disappointment with the divided opposition and frustration that exhausted Venezuelans were not taking to the streets.
"I am not going to vote. For what?" said Freddy Álvarez, a 43-year old merchant arguing with his friend about the election at a bakery in western Caracas. Last year, tens of thousands joined anti-government marches, but those protests have largely died out.
"To see a change here, people need to take the streets again," Álvarez said. "We will not overthrow Maduro with votes. I do not understand why people are so apathetic."
A salsa-loving former truck driver and union leader, Maduro, 55, has sought victory by doling out food at rallies and railing against "el Imperio" - the Empire, as he often labels the United States. Pro-government vans with loud speakers roamed the streets, evoking the name of Chávez and urging Maduro supporters to turn out.
"Let's vote! Let's defend President Chávez's legacy! Don't stay at home!" a loudspeaker boomed from one of the vans.
Some Maduro backers said they agreed that outside enemies and domestic oligarchs were to blame for the country's woes.
"All the difficulties we're having are because of an economic war," said Obdulia Herrera, a 65-year old retired teacher. "Foreign countries are blocking everything, including medicines. If the opposition wins, we won't get benefits anymore."
Critics of Maduro say his government has committed fraud to win the last three elections and predicted that the incumbent would ensure his victory.
"There are no conditions under which the electoral commission will announce results that aren't the ones they have already prepared," said Juan Pablo Guanipa, an opposition leader.
He added, "The real truth is that this is an orchestrated farce to keep Maduro in power without popular support."
Some analysts, however, say Maduro could win without vote rigging, because his Government has already created an uneven playing field by barring his strongest opponents and monopolising media time.
In addition, many Venezuelans said they feared they or their relatives would lose government jobs if they failed to support Maduro.
Even more were worried about losing access to subsided government food boxes - known as CLAP boxes - that have become the main source of sustenance for millions.
