The first major city to mark the start of 2009 was Auckland, New Zealand, with a spectacular display of fireworks from its Sky Tower.
More than one million people turned out in the Australian city of Sydney for its largest-ever pyrotechnics show.
In Hong Kong, half a million people gathered around the historic harbour for the new year countdown.
In Thailand, performers in traditional dress carried candles during a Buddhist ceremony in the capital, Bangkok.
In Petaling Jaya, Malaysia, party-goers danced in front of a laser and water show in the early hours of 2009.
In Japan, many went to Tokyo's Zojoji Buddhist temple to offer a prayer at the end of the year.
From the Vatican, Pope Benedict XVI urged people not to be afraid during uncertain times, but to help each other.
In London, 400,000 attended a fireworks display and watched video messages from the likes of London Mayor Boris Johnson and Homer Simpson, while Elton John performed at the O2 Arena.
In Greece, Palestinian protesters staged a demonstration near an outdoor concert in Athens during New Year celebrations, chanting slogans and burning Israeli, US and EU flags.
In Valencia, Spain, revellers took part in an unusual new year's tradition - a red underwear race.
Bill and Hillary Clinton joined the kissing crowds in New York's Times Square, after the ball dropped at midnight.