SEOUL — A former Hyundai CEO known as “The Bulldozer” for his determination to get things done rolled over all opposition and financial fraud allegations to win South Korea’s presidency today, ending a decade of liberal rule.

Lee Myung-bak, who turned 66 on election day and has also served as the mayor of Seoul, earned the landslide victory on a wave of discontent with the incumbent president, Roh Moo-hyun, whom many believe bungled the economy and dragged down the country’s rapid growth.

The rise to power of Mr. Lee’s conservative Grand National Party was expected to herald closer ties with the American and a more critical view of relations with communist North Korea, which has been lavished with aid by Mr. Roh’s administration.

The National Election Commission said Mr. Lee had 48.7% of the vote after all ballots were counted. The liberal candidate, Chung Dong-young, was a distant second with 26.2%.

It was the biggest margin of victory in any South Korean presidential election. The candidate with the most votes wins and there are no run-offs. Turnout was a record low 63% of 37.7 million eligible voters.

South Koreans apparently wanted change so badly that they were willing to overlook accusations of ethical lapses that dogged Mr. Lee throughout his campaign.

Just days before the election, parliament approved an independent counsel investigation into allegations that Mr. Lee manipulated stock. The investigation is to be completed before the February 25 inauguration, and Mr. Lee has said he will step down if found at fault.

“After all, the people chose the economy over morality,” the Maeil Business Newspaper wrote in an editorial for its Thursday editions.

Mr. Lee emphasized the economy in his campaign with a “747” pledge — promising to raise annual growth to 7%, double the country’s per capita income to $40,000 and lift South Korea to among the world’s top seven economies. He also proposed a “Grand Canal” linking Seoul to the southern port city of Busan that would improve transport and be a tourist attraction.

“Today, the people gave me absolute support. I’m well aware of the people’s wishes,” Mr. Lee told supporters at his party’s headquarters. “I will serve the people in a very humble way. According to the people’s wishes, I will save the nation’s economy that faces a crisis.”

Mr. Lee heads to office amid progress in the long-running standoff over North Korea’s nuclear weapons program, fostered by American political and economic concessions to Pyongyang.

The president-elect is expected to tie aid to continued compliance with international demands in the atomic dispute in line with Washington’s wishes, but was not expected to make any dramatic change in assistance while the North remains on the path to disarmament.

The Bush administration congratulated Mr. Lee on his victory, saying it expected close cooperation with his government over the North Korean nuclear dispute.

“We have a long history of cooperation and friendship with South Korea and fully expect that’ll continue with this new government,” a State Department spokesman, Tom Casey, said.

Hundreds of supporters watching the results on a giant TV in front of the Grand National Party’s headquarters burst into song this evening as Lee’s victory became clear.

“I am very happy and it is like retaking democracy after a decade” of liberal rule, a housewife in her 50s, Park Mi-won, said.

Mr. Lee rose from the poverty that gripped the peninsula after the 1950-53 Korean War and worked as a janitor to put himself through college.

He first gained prominence as head of Hyundai’s construction unit, which symbolized South Korea’s meteoric economic rise in the 1960s and 70s. As Seoul’s mayor between 2002 and 2006, he undertook beautification projects in the city that earned him environmental credibility and were viewed as redemption for earlier eyesores he built with Hyundai in the country’s haste to develop.

It was during his three decades with the Hyundai Group that Mr. Lee earned the nickname “Bulldozer” for his drive to push through challenges. In one instance, he completely took apart a bulldozer to study its mechanism and figure out why it kept breaking down.

“I feel good that the right person was elected. I voted for him because he is an economic president,” a housewife who was among crowds gathered to watch vote results near a restored stream in central Seoul that was Lee’s landmark project as mayor, Lee Myung-ja, 60, said. “I hope President Lee Myung-bak will focus on economic growth so as to make the people better-off.”

Taking the luster off Mr. Lee’s victory were lingering allegations of involvement in a stock manipulation case in which a former business associate faces criminal charges for illegal gains of millions of dollars. A video released Sunday by his liberal rivals showed Mr. Lee saying in 2000 that he founded the firm at the center of the case.

Mr. Lee has said the taped comments were taken out of context and denied the allegations, but consented to the independent counsel to clear his name. He is the country’s first president-elect to face a criminal probe.

By South Korean law, a president-elect can be prosecuted but he would receive immunity from most criminal lawsuits after inauguration.