With 94 percent of the ballots counted, 54 percent had voted for the constitutional amendment, said National Electoral Council chief Tibisay Lucena, the Associated Press reported.
Chavez celebrated the results at the presidential palace, shouting from the balcony, "The doors of the future are wide open," quoted the BBC.
"Those who voted 'yes' today voted for socialism, for revolution," he said.
Critics of the removal of the 12-year term limit say it brings Venezuela closer to a dictatorship, but opposition leaders said they would not contest the vote, which international observers maintained was free and fair.
"We accept this result," student leader David Smolansky, 23, said at opposition campaign headquarters, according to the AP. "We're still standing. We're committed to Venezuela."
An all-out campaign by Chavez and a broadening of the referendum to include all politicians, not just the president, helped garner support for the measure and bring its decisive win, said Shannon O'Neil, Douglas Dillon fellow for Latin America studies at the Council on Foreign Relations.
The referendum's passage reaffirmed Chavez's support and means he can run again in 2012, but more immediately, he will have to contend with a worsening global economy and declining oil prices, said O'Neil.
"What's really going to affect Venezuela in the next few years is the economy. Chavez enjoyed quite a substantial political honeymoon -- almost 10 years -- in part because of strong political support and a strong base, but also in large part due to high oil prices and an oil-driven economy," she said.
The country's oil wealth enabled Chavez to provide broad social programs, such as health care and education, which raised his popularity. But now that oil prices have fallen from nearly $150 a barrel to about $40, the public will start to feel the effects from the decreasing revenues, and the inefficiencies of some of his policy decisions, such as nationalizing industries and limiting the prices of certain goods, she said.
"The pain of the economic downturn hasn't hit yet, but it's going to hit this year and it's definitely going to hit in 2010," said O'Neil. "So actually the referendum is the least of Chavez's worries." His re-election will be the real difficulty, she added.
Mauricio Cardenas, a senior fellow and director of the Latin American Initiative at the Brookings Institution, said he expected Chavez to continue promoting reforms that will bring more state control, not just of the economy but of other programs such as education and health.
"What Venezuela's going to see in the next couple of years is a declining economy with full speed reforms that will make the government stronger," Cardenas said. "And whether that's sustainable and whether that's going to result in his re-election in 2013, that's uncertain."