Former Venezuelan opposition presidential candidate Edmundo González has fled into exile after being granted asylum in Spain, delivering a major blow to millions who placed their hopes in his upstart campaign to end two decades of single-party rule.

The surprise departure of the man considered by Venezuela’s opposition and several foreign governments to be the legitimate winner of July’s presidential race was announced late Saturday night by Venezuela’s vice president, Delcy Rodríguez.

She said the government decided to grant Mr. González safe passage out of the country, just days after ordering his arrest, to help restore “the country’s political peace and tranquility.”

Neither Mr. González nor opposition leader Maria Corina Machado has commented.

Meanwhile, Spain’s center-left government said the decision to abandon Venezuela was Mr. González’s alone and he departed on a plane sent by the country’s air force.

Foreign Minister José Manuel Albares told Spanish national broadcaster RTVE that his government will grant Mr. González political asylum as he has requested. Mr. Albares spoke while en route to China with Spanish Prime Minister Pedro Sánchez on a state visit.

“I have been able to speak to (González) and once he was aboard the airplane he expressed his gratitude toward the Spanish government and Spain,” Mr. Albares said. “Of course I told him we were pleased that he is well and on his way to Spain, and I reiterated the commitment of our government to the political rights of all Venezuelans.”

Mr. Sánchez said in a speech Friday, before Mr. González’s departure was announced, that the opposition leader was “a hero whom Spain is not going to abandon.”

Mr. Albares said that Mr. González had spent an unspecified number of days at the Spanish Embassy in Caracas before his departure.

A Spanish official with knowledge of details on Mr. González’s departure said that his government did not discuss Mr. González’s exit with Mr. Maduro’s administration. The official spoke on condition of anonymity in line with ministry protocols.

Mr. González, a 75-year-old former diplomat, was a last minute stand-in when Ms. Machado was banned from running. Previously unknown to most Venezuelans, his campaign nonetheless rapidly ignited the hopes of millions of Venezuelans desperate for change after a decade-long economic freefall.

While President Nicolás Maduro was declared the winner of the July vote, most Western governments have yet to recognize his victory and are instead demanding that authorities publish a breakdown of votes. Meanwhile, tally sheets collected by opposition volunteers from over two-thirds of the electronic voting machines indicate that Mr. González won by a more than 2-to-1 margin.

The tally sheets have long been considered the ultimate proof of election results in Venezuela. In previous presidential elections, the National Electoral Council published online the results of each of the more than 30,000 voting machines but the Maduro-controlled panel did not release any data this time, blaming an alleged cyberattack mounted by its opponents from North Macedonia.

Attorney General Tarek William Saab, a staunch Maduro ally, sought Mr. González’s arrest after he failed to appear three times in connection with a criminal investigation into what it considers an act of electoral sabotage.

Mr. Saab told reporters the voting records the opposition shared online were forged and an attempt to undermine the National Electoral Council.

Experts from the United Nations and the Carter Center, which at the invitation of Mr. Maduro’s government observed the election, determined the results announced by electoral authorities lacked credibility. In a statement critical of the election, the U.N. experts stopped short of validating the opposition’s claim to victory, but they said the voting records it published online appear to exhibit all of the original security features.

Exiled opposition politician Franco Casella told RTVE that Mr. González would continue to campaign against the regime from abroad in what he called a dual leadership role with Ms. Machado, who Mr. Casella said remains in hiding in Venezuela.

He said he understood that some people who opposed Mr. Maduro might feel “orphaned” by Mr. González’s departure but, he said, “this is going to be capitalized positively …. and my message is that this is not the time for tears, it is time for us to remain united against the dictatorship.”

Spain has been a major point of exodus for Venezuelans, particularly of those leading the opposition to Mr. Maduro’s regime. They include Leopoldo López, who fled to Spain to reunite with his family in 2020, and Antonio Ledezma, who left in 2017.

Some 44,000 Venezuelans immigrated to Spain in the first six months of this year. The last government statistics from 2022 said that some 212,000 Venezuelans were then residing in Spain.