BUENOS AIRES — Argentine voters handed a victory to Mauricio Macri in the country’s presidential election on Sunday, delivering a mandate to an opposition political figure seeking to roll back some of the protectionist economic measures of the departing president, Cristina Fernández de Kirchner.

With votes from 99 percent of polling places counted, Mr. Macri, the mayor of Buenos Aires and a former president of Boca Juniors, one of Argentina’s most popular soccer teams, was leading with 51.4 percent of the vote, according to election officials, against 48.5 percent for Daniel Scioli, a former speedboat racer and vice president under former President Néstor Kirchner, who died in 2010. Mr. Scioli conceded defeat on national television on Sunday night.

Running a largely nonconfrontational campaign in a society that has grown increasingly polarized under Mrs. Kirchner, who succeeded her husband in 2007, Mr. Macri, 56, stunned the political establishment in October by forcing the race into a runoff and maintaining his surge in recent weeks. He ran to the right of his rivals, blending plans to overhaul the economy and promote the tolerance of various points of view on social issues.

Mr. Macri’s relatively narrow victory revealed deep fissures in Argentina after 12 years of governance by Mrs. Kirchner and her husband, with many voters expressing concern over the direction of the economy and frustration with Mrs. Kirchner’s blistering attacks on critics in the news media, business establishments and rival political parties.