Argentines on Sunday chose Javier Milei, a far-right libertarian who has drawn comparisons to Donald J. Trump, as their next president, a lurch to the right for a nation struggling under an economic crisis and a sign of the enduring strength of the global far right.

Mr. Milei, 53, an economist and former television personality, has burst onto the traditionally closed Argentine political scene with a brash style, an embrace of conspiracy theories and a series of extreme proposals that he says are needed to upend a broken economy and government.

Sergio Massa, 51, Argentina’s center-left economy minister, conceded defeat even before official results were released because the campaigns’ early numbers showed he had been defeated.

As president, Mr. Milei has pledged to slash spending and taxes, close Argentina’s central bank and replace the nation’s currency with the U.S. dollar. He has also proposed banning abortion, loosening regulations on guns and only considering countries who want to “fight against socialism” as Argentina’s allies, often naming the United States and Israel as examples.

Mr. Milei’s election is a victory for the global far-right movement that gained strength with the election of Mr. Trump and similar politicians, such as Jair Bolsonaro of Brazil, but has faltered in recent years with their electoral losses. Mr. Bolsonaro and Spain’s far-right Vox party have cheered on Mr. Milei, and his last interview with an English-language outlet was with the former Fox News host Tucker Carlson.

Yet some political analysts said that Mr. Milei’s ascent reflects many Argentines’ desperation for change rather than support of his far-right ideology.