A 12 minute fireworks display in Sydney marked the New Year for Australia.
A giant four-coloured rainbow was beamed from Sydney harbour bridge as a symbol of hope and renewal.
Seven tonnes of fireworks were fired from barges, the foreshore and from the harbour bridge.
The display included cloud-shaped fireworks, butterflies and strobing golden waterfalls from the base of the bridge.
AFP reported about 1.5 million people watched the show light up the harbour.
In her New Year message, Prime Minister Julia Gillard said 2012 would be a time for new hope and new beginnings.
Celebrations in central Melbourne were interrupted by a fire atop the Melbourne Arts Centre.
The ABC reports fireworks caused the blaze on the spire of the centre. Burning debris fell onto the roof of the centre below.
Melbourne's celebrations attracted about 600,000 people to the city centre.
Hong Kong staged a similar fiesta over Victoria harbour, but the mood was more sombre in Japan.
Thousands of people in Tokyo released balloons carrying hand-written wishes for the New Year.
Many wished for a better year, following the earthquake and tsunami that brought devastation in March.
Fireworks set off and the Tokyo Tower lit up in blue as the clock struck midnight.
In Moscow, the sale of all alcohol was banned in Red Square to prevent revelry getting out of hand.
Europe and US
In Rome, Pope Benedict XVI said humanity awaited 2012 with apprehension, but also hope for a better future.
United Nations Secretary-General Ban Ki-Moon said he wants to sustain the moves towards democracy that protestors had sought in the Arab uprising.
In London, a quarter of a million people gathered along the River Thames as fireworks began at the midnight chimes of Big Ben.
Throngs of revelers crowded into the streets around Times Square in New York amid tight security.
They were there to send off a year marked by the grim anniversary of the September 11 attacks on the city in 2001 and give a boisterous welcome to 2012.
The highlight of the celebrations was to be the lowering of a large lighted crystal ball for the last minute of the old year, a tradition started in 1907.