Hundreds of thousands of people packed into New York's Times Square to welcome in 2006.
Party-goers crowded Rio de Janeiro's Copacabana beach for the city's largest firework display.
In London, there was a large firework display along the River Thames, lighting up the London Eye.
It was a chilly night in Berlin, where celebrations took place around the Brandenburg Gate.
In Paris, the New Year was marked by street celebrations as half a million revellers thronged around the city's famous landmarks.
A ban on alcohol in Moscow's Red Square did not appear to dampen spirits among the party-goers.
The Australian city of Sydney kicked off the New Year celebrations in style with a massive fireworks display.
Fireworks ushered in the New Year in Shanghai. The Chinese lunar new year begins later this month and will mark the year of the dog.
In Tokyo, Buddhist worshippers struck a giant bell to bring in the New Year at Zojoji temple.