A court ordered the release of Roberto Di Matteo of Italy, Filippo Rossi of Switzerland and Jesus Medina of Venezuela, according to the National Union of Press Workers, which tweeted a picture of a relieved Medina posing with his release card.
Swiss and Italian diplomats said they had intervened to ensure the men's proper treatment and secure what the Swiss foreign ministry described as a swift resolution.
Italy's Minister of Foreign Affairs, Angelino Alfano, added his government had paid "great attention" to the case.
"For us it is good news," he said.
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The rights group Foro Penal, which had provided legal assistance, said the men and their television crew had entered Tocoron prison -- considered one of the country's most violent -- to conduct an investigation.
Critics say Venezuelan prisons are overpopulated and inmates are malnourished, despite government plans to reduce inmate populations.
'We reject the harassment'
The press union on Saturday released a photograph of the three journalists taken from the back, apparently handcuffed and escorted by two military personnel.
"They had an invitation to enter Tocoron," the union said in a statement. "They had registered to enter when they were barred access and then arrested. It seems there was a counter-order to bar them access."
Venezuela's Foreign Press Association sharply denounced the men's treatment, saying, "We reject the harassment and detention of journalists as a means to intimidate the press."
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Late last year, rights group Una Ventana a La Libertad estimated that there were some 88,000 inmates across a country with an official prison capacity of 35,000.
President Nicolas Maduro's government, which says it is being unfairly disparaged in national and international media, says it has successfully applied measures to pacify prisons and raise their standards to international norms.
Di Matteo is a videographer for Italian daily Il Giornale who has regularly collaborated with freelance journalist Rossi.
Rossi has also worked with regional Swiss daily Corriere del Ticino, while Medina is a photojournalist for anti-government website DolarToday.