Mexico's telecom mogul Carlos Slim Helu grabbed second place with a tidy nest egg of 60 billion dollars, up from 49 billion last year.
Buffett, who announced in 2006 he was giving the majority of his fortune to the Bill & Melinda Gates Foundation, saw his wealth spike mostly due to the rising value of his Berkshire Hathaway stock.
"The amazing thing about Buffett going to the top of the list is that he did it at a time when he was giving away his money," said Steve Forbes, the magazine's editor in chief.
In total, this year's list sees 1,125 people around the world making the billionaire's list, up from 946 last year. Their total net worth stands at 4.4 trillion dollars, up from 3.5 trillion dollars in 2007.
"This past year was an amazing one around the world