Buffett, the founder of the Omaha, Neb.-based Berkshire Hathaway Inc. and one of the world's richest men, co-hosted the fundraiser, which brought in at least $1 million for Clinton's presidential effort.
Buffett, a Democrat, has not formally endorsed Clinton, but guests at the dinner said he called the New York senator "the person to run the country."
Buffett is also expected to host an event for rival Democrat Barack Obama later this summer and has spoken favorably about the presidential prospects of New York Mayor Michael Bloomberg, who recently left the Republican Party to become an independent.
Known in business circles as the "Oracle of Omaha," Buffet joined Clinton onstage after the fundraiser to field questions from attendees about his views on American competitiveness, smart investing, education and even the global nuclear threat.
Central to Buffett's message was the notion that he and other privileged Americans — those who had drawn the "lucky tickets" — had an obligation to provide for those less fortunate.
"We have the chance in 2008 to repair a lot of damage," Buffett said. "We have a wonderful economy. The market system works in this country. Our problem is how we conduct ourselves in the world."
While expressing optimism about the U.S. role in the global economy, he warned that the nation needed to increase exports and cease being a debtor nation. He also called for an overhaul of the tax code, which he said unfairly favored rich men like him.
"Let's just see what Americans, chosen, are paying compared to the people who clean their offices," he said, referring to tax breaks given to those with higher incomes.
Buffett said he earned $46 million in 2006 and had paid a lower tax rate than one of the secretaries in his office, who earned about $60,000.