Celebrations are being held around the world to mark the new year, with Auckland holding the first major event of 2013.
Crowds also gathered around Sydney harbour for the city's famous annual firework display.
Fireworks exploded over the Sky Tower in Auckland as midnight struck.
Two hours later, seven tonnes of pink and gold fireworks lit up the Sydney harbour bridge and the Opera House.
AAP reports the colour scheme and soundtrack were chosen by Kylie Minogue to mark her 25 years in show business.
The display opened with a large pair of red lips marking the official countdown to midnight.
"It's been a huge year for me and the finish line is tonight," Minogue said.
"How's everyone feeling," she asked, as she pressed a button to trigger the display.
Sydney Lord Mayor Clover Moore said about 1.5 million spectators were expected to line Sydney Harbour to watch the fireworks, with another two million watching the $A6.6 million event on television.
Big shows are planned in many other cities globally.
Myanmar for the first time welcomed in new year with a big public fireworks display in the former capital Rangoon.
Thousands of people attended the event, which also included live performances and countdowns from other parts of the world.
In India, the armed forces have cancelled large New Year's eve parties, reflecting a sombre mood across the country after the gang rape and murder of a student in New Delhi.
High-end clubs, politicians and ordinary people also called off their celebrations as a mark of respect for the woman who died on Saturday two weeks after her brutal assault.
Festivities were held as usual in European cities including Moscow, Paris and Berlin.
In London, huge crowds made their way to Trafalgar Square and the banks of the river Thames to hear Big Ben strike midnight, to the backdrop of a fireworks display.
New York marked the occasion with the traditional New Year's Eve countdown and ball-drop over Times Square.