World leaders used the occasion to speak of their hope for 2010 compared with the difficulties many countries faced in 2009.
North Korea called for an end to hostile relations with the US in a New Year message, while French President Nicolas Sarkozy said: "The year that is ending has been difficult for everybody.
"No continent, no country, no sector has been spared."
A massive fireworks display, attended by an estimated 1.5 million people, took place in Sydney, Australia, with some 5,000kg of explosives sent up around the famous harbour bridge.
Fireworks were launched from the bridge itself, from boats in the harbour and from buildings around the waterfront.
The Japanese capital, Tokyo, greeted the new year in traditional style, with bells rung in temples at midnight.
The city's Sensoji Temple was draped with banners wishing visitors a happy new year.
Thousands of people in Beijing gathered in a shopping centre to mark the change of the Lunar New Year.
And in Hong Kong, about half a million revellers crowded the harbour front to watch fireworks set off from the top of city skyscrapers.
Some two million people crowded onto Copacabana beach in Rio de Janeiro to dance to DJs and music acts and watch fireworks sent up over the sea.
In the Philippines, new year celebrations were marred as hundreds of people were injured by firecrackers and celebratory gunfire.
Despite heavy snowfall and temperatures down to -10C (14F), more than 120,000 Russians were on Red Square in Moscow to see fireworks and hear President Dmitry Medvedev congratulate them on "bearing up" over the past year.
"The past year was not a very easy one for our country, and I want to thank you all for bearing up together," he said.
Revellers in New York's Times Square were showered in confetti at midnight
In Spain, which took over the rotating EU presidency at midnight, thousands of people who had gathered in the capital, Madrid, saw images of the EU flag light up the central Sol square.
Others around the world chose to mark the occasion by attending churches and temples to pray for the coming year.
At the Vatican, the Pope - apparently unaffected by the Christmas Eve assault where he was knocked to the ground - returned to St Peter's Basilica to lead a year-end service.
In the French capital, Paris, the Eiffel Tower was illuminated by a pulsating, multi-colour display, described by city officials as "a giant Christmas tree with tinsel".
London's spectacular firework display - which began on the final chimes of Big Ben - centred on the huge London Eye wheel on the banks of the River Thames.
In Venice, revellers rang in 2010 with wet feet because of a high tide at midnight.
As the US celebrated, security was tight in New York's Times Square, with partygoers banned from taking rucksacks or large bags into the area.
Revellers watched the traditional descent of the crystal ball and on the stroke of midnight were showered in confetti mixed with some 10,000 hand-written wishes for the year head, including cures for diseases and the safe return of troops from conflicts.
In some parts of the world, people could witness a "blue moon" overnight. This has nothing to do with the moon's colour, and is simply the second full moon in a month.
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