María Corina Machado, the Venezuelan opposition leader who built a powerful social movement and became the most significant threat and detested adversary to the country’s longstanding authoritarian regime, was awarded the Nobel Peace Prize on Friday.

A conservative former member of the national assembly, Ms. Machado has been a driving force in opposing a quarter century of socialist rule that has grown increasingly repressive under President Nicolás Maduro. She has been living in hiding since last year, when Mr. Maduro cracked down on the opposition after claiming victory in an election that was widely seen by independent analysts as fraudulent.

The Norwegian Nobel Committee praised Ms. Machado for her “tireless work promoting democratic rights for the people of Venezuela and for her struggle to achieve a just and peaceful transition from dictatorship to democracy.”

Ms. Machado has largely avoided commenting on whether Mr. Maduro’s removal should involve U.S. military intervention in Venezuela. But she has been a strong supporter of President Trump’s military buildup in the Caribbean, where American forces have destroyed several suspected drug boats in international waters, killing at least 21 people.

“I totally support the international deployment and coalition that’s working in the Caribbean to stop the flow of illegal drug income to the regime,” Ms. Machado told the BBC last week.

The Norwegian Nobel Institute was able to reach Ms. Machado by telephone a few moments before the prize was announced to tell her she had been selected. “Oh my God,” she said in a video posted by the committee on social media. “Well, I have no words.”

In her campaigns opposing the Venezuelan government, she has spent more than two decades building relationships in Washington, with Democrats and Republicans alike. In 2005, she was received in the White House by President George W. Bush, and she has been praised extensively by Marco Rubio, the secretary of state and former Florida senator.

She argues, like Mr. Trump, that Mr. Maduro poses an enormous security threat to the region.

“This is about saving lives,” she told Fox News last month, “not only Venezuelan lives, but also lives of American people, because as you have said, and we have heard, Maduro is the head of a narco-terrorist structure of cooperation.”

Yet the announcement of Ms. Machado’s selection for the peace prize seemed to have been greeted with disappointment by the White House, after President Trump talked openly for months about his desire for the prize himself. The White House communications director, Steven Cheung, said the Nobel committee had “proved they place politics over peace.”

“President Trump will continue making peace deals, ending wars and saving lives,” Mr. Cheung said in a social media post.

A mother of three adult children, all of whom live abroad, Ms. Machado, 58, hails from a wealthy and staunchly Catholic family. She attended an elite Catholic girls’ school in Caracas and a boarding school in Wellesley, Mass.

She studied engineering at Andrés Bello Catholic University, and then took a position in her family’s steel business, Sivensa, parts of which were expropriated in 2010 by President Hugo Chávez, who sent soldiers to take over seven of the company’s plants as part of his socialist nationalization program.

Ms. Machado had already become a political activist by then, running a voter rights group, Súmate, that led a failed effort to recall Mr. Chávez, who died in 2013. An emblematic moment came in 2012, when Ms. Machado was a legislator and she clashed with Mr. Chávez in a televised debate, accusing him of robbing everyday Venezuelans through expropriation.

Mr. Chávez mocked her as being beneath his concern. “Eagles don’t hunt flies,” he told her.

Venezuela’s opposition struggled through years repression and division under Mr. Chávez and then his ally and successor, Mr. Maduro, when the government crushed protests and arrested dissidents, and the economy collapsed, all contributing to an enormous exodus from the country.

But last year, Ms. Machado corralled the fractious opposition, playing a galvanizing role in the campaign for the July presidential election. After a court ruled in January 2024 that she was barred from the ballot, she campaigned behind a little-known diplomat named Edmundo González.

With rosaries swinging from her neck, Ms. Machado was greeted by adoring crowds as she traveled across the country, visiting small towns and slums that had once provided the core of support for the country’s socialist takeover. In the city of Guanare, in western Venezuela, one voter said she believed that this time around “the fly is going to trap the eagle.”

Ms. Machado has championed free markets and vowed to “bury socialism forever.” And she has said that the politician she most admired was Margaret Thatcher.

But on the campaign trail last year, she mostly tempered partisan economic talk and focused on what united most Venezuelans: the pain of family separations and the loss of political freedoms.

Ms. Machado and her allies sought to show the election had been fraudulent by gathering a physical printout of the voting tally from the majority of voting machines after the polls closed. By the opposition’s count, Mr. González defeated Mr. Maduro by more than 2 to 1.

Unable to celebrate her Nobel win openly, Ms. Machado’s supporters greeted her winning the peace prize with private joy and hope on Friday.

A brutal crackdown instituted by Mr. Maduro last year to remain in power forced many in the opposition into hiding. Hundreds of her supporters remain in jail.

Top Trump Administration officials have in recent weeks stepped up efforts to remove Mr. Maduro from power, with officials discussing a broad campaign that would escalate military pressure to try to force him out.

The efforts are being led by Mr. Rubio, who in addition to his role as secretary of state is national security adviser. Mr. Rubio has argued that Mr. Maduro is an illegitimate leader who oversees the export of drugs to the United States, which he says poses an “imminent threat.”

An adviser to Ms. Machado told The New York Times last month that leaders of the Venezuela opposition have been speaking to the Trump administration about how to counter Mr. Maduro. Pedro Urruchurtu, the adviser, said that the opposition had developed a plan for the first 100 hours after Mr. Maduro’s ouster that would involve a transfer of power to Mr. González.

“What we’re talking about is an operation to dismantle a criminal structure,” Mr. Urruchurtu said, adding: “It has to be done with the use of force, because otherwise it wouldn’t be possible to defeat a regime like the one we’re facing.”

Reporting was contributed by Anatoly Kurmanaev, Edward Wong and Erin Mendell.