In Sydney, Lord Mayor Clover Moore said about 1.5 million spectators were expected to line the harbor to watch the 6.6 million Australian dollar ($6.9 million) fireworks display, while another 2 million Australians among a population of 22 million would watch on television.
"This is really putting Australia on the map in terms of welcoming people to the new year," Moore told reporters before the event.
Thousands lined the harbor shore in festive crowds under a blue summer sky by late afternoon, their number undiminished by Australian government warnings that the Washington deadlock on the U.S. debt crisis was partly to blame for a slowing Australian economy.
Australian pop singer Kylie Minogue was hosting the event.
Florida tourist Melissa Sjostedt was among the thousands gathered near a southern pylon of the bridge. She said seeing the fireworks would fulfill an ambition that began a decade ago when she read about them in National Geographic magazine.
"Ever since that, I've always wanted to see this for real, live, in person," she said.
New Yorker Mathieu Herman said he had flown to Australia specifically for the New Year celebrations on the harbor.
"I saw it last year on TV and it looked fabulous. I said to myself it's something I've just got to do," Herman said.
Despite a somber mood in the Philippines due to devastation from a recent typhoon, a key problem for authorities remained how to prevent revelers from setting off huge illegal firecrackers — including some nicknamed "Goodbye Philippines" and "Bin Laden" — that maim and injure hundreds of Filipinos each year, including many children.
A government scare tactic involving doctors displaying brutal-looking scalpels used for amputations for firecracker victims has not fully worked in the past so health officials came up with a novel idea: Go Gangnam style.
A government health official, Eric Tayag, donned the splashy outfit of South Korean star PSY and danced to his Youtube hit "Gangnam Style" video while preaching against the use of illegal firecrackers on TV, in schools and in public arenas.
"The campaign has become viral," Tayag said. "We've asked kids and adults to stay away from big firecrackers and just dance the Gangnam and they're doing it."
Hong Kong feng shui master Raymond Lo predicted 2013 would be less turbulent than 2012 because the Chinese New Year in February will usher in the year of the snake, bringing an end to the year of the dragon, which was associated with water. Water is one of the five elements in feng shui theory, the Chinese practice of arranging objects and choosing dates to improve luck.
"Water is fear. So that's why we have had so much turbulence especially in the winter months," such as doomsday prophecies, school shootings and concerns about the fiscal cliff, said Lo.
"But the good news is that the coming year of the snake is the first time that fire has come back since 2007. Fire actually is the opposite to water, fire is happiness. So therefore the year of the snake is a much more optimistic year. So you can see signs of economic recovery now," he added.
"The positive thing is that people are very optimistic, therefore it will have a very strong drive on the economic recovery. We expect the stock market will do well, the property market will do well," Lo said.
Associated Press writers Aye Aye Win in Yangon, Myanmar; Jean Lee in Pyongyang, North Korea; Chris Brummitt in Jakarta, Indonesia; Kelvin Chan in Hong Kong; Ashok Sharma in New Delhi; and Jim Gomez in Manila, Philippines, contributed to this report.