Voter turnout was low, about 45 percent, in keeping with a consistent fall in electoral participation since the return to democracy in Chile after 17 years of military dictatorship. Marta Lagos, director of the polling group Latinobarómetro, said the apathy could be explained in large part by a general view that politicians are corrupt and public institutions are not to be trusted.

Four members of Congress have been stripped of immunity from prosecution and dozens of politicians, their associates and relatives are being investigated for illegal campaign financing in earlier elections, influence-peddling and other white-collar crimes.

“People are disappointed with our democracy,” Ms. Lagos said. “Parties and politicians have been totally discredited, and there is a widespread perception that all politicians are corrupt demons, that there is no one to vote for. People want a major transformation of the political system and corrupt politicians put in jail, and maybe then they will get out and vote.”

On Sunday morning, a group of demonstrators forced their way into Mr. Piñera’s campaign center to protest the elections. More than 20 were arrested. In the Araucanía region, about 400 miles from Santiago, the capital, unidentified individuals intercepted a bus that was going to transport voters from rural areas to voting places and set it on fire.

In all, eight people — an ideologically diverse array of candidates — were on the ballot on Sunday.

Both the right-wing opposition and the governing coalition, New Majority, had two candidates competing against each other for the presidency. Mr. Piñera was flanked to the right by the extremely conservative José Antonio Kast, who advocates building a physical barrier along Chile’s northern border with Peru and Bolivia, withdrawing from international treaties and organizations, and abolishing a recently approved law permitting abortions in some cases.

Against all predictions, Mr. Kast drew nearly eight percent of the vote.

Mr. Guillier was competing with a political ally, Carolina Goic, of the more conservative wing of the centrist Christian Democratic party. The remaining three candidates were all to the political left of Mr. Guillier.

Ms. Bachelet will finish her four-year term in March. Under Chile’s Constitution, she cannot run for immediate re-election. Battered by criticism, sagging popular support and a high-profile corruption case involving her son and daughter-in-law, Ms. Bachelet has publicly vowed that she will not seek any elected office in Chile in the future.