Firework displays, parties and other celebrations are taking place around the world to welcome 2011.
Thousands of revellers took to the streets in New Zealand - the first major country to see in the new year, while in the Australian city of Sydney an estimated 1.5 million watched a fireworks extravaganza.
In New Zealand's biggest centre, Auckland, thousands of people flocked into the central city to see co-ordinated fireworks displays which the council says was the largest since the millennium celebrations in 2000.
Crowds gathered in Sydney to watch what has been hailed as the biggest New Year's Eve fireworks display to date. Seven tonnes of fireworks were used during the 12-minute extravaganza.
In the main city of flood-hit Queensland, Brisbane, police say crowd numbers for the midnight fireworks display was 15,000, down on the previous year's total of 40,000.
In Hong Kong, hundreds of thousands of people gathered along Victoria Harbour to watch fireworks explode from the city's most prominent buildings, the BBC reports.
At Japan's Zojoji temple in Tokyo, monks chanted as visitors packed in to count down until midnight. Thousands released a mass of silver balloons carrying notes with their hopes for the future.
In Taipei, the capital of Taiwan, fireworks formed the shape of a dragon spiralling up the tallest skyscraper.
New York's municipal authorities and warmer weather combined to clear the streets following the snowstorm which blanketed the city this week, allowing hundreds of thousands to gather for the famous Times Square ball drop at midnight.
In London, hundreds of thousands of people watched a dazzling fireworks display on the Thames as Big Ben struck midnight.
Crowds have gathered in Madrid's Puerta del Sol square to take part in "Las Uvas" (The Grapes), a tradition in which people eat a grape for each of the 12 chimes of midnight.
As the new year arrived, Estonia became the 17th country to join the euro currency, with Prime Minister Andrus Ansip marking the event by withdrawing euros from a cash point.
The tiny Pacific nation of Kiribati was the first to welcome in the new year. The religious island nation was set to mark the event with church and village services.