Security was tight for the festivities in major cities worldwide, with 25,000 police and paramilitary gendarmes on duty in France against a background of fears of a repeat of the urban violence seen in towns and cities nationwide last month.
However, despite the torching of about 250 cars across the country, police reported no serious outbreaks of unrest, and tens of thousands of revellers welcomed the arrival of 2006 in Paris's most famous avenue, the Champs-Elysees.
Street parties and glittering displays marked the festivities from Sydney to London, with crowds packing the banks of the River Thames to see the 10-minute blaze of fireworks focused on the London Eye.
The city's landmark ferris wheel was lit up in the colours of the five Olympic rings to celebrate London being awarded the 2012 Games.
The New Year festivities gave Londoners a chance to put in the past the deadly 7 July attacks on the capital's transport network.
Tony Blair, the British prime minister, in his New Year message said: "We will not let our resolve slip to tackle the dangers we face, both at home, as so tragically illustrated on 7 July, and abroad."
Tony Blair: We will not let our
However, as the clock struck 12, a strike on the London Underground trains threatened to make the journey home grim for some, once the fireworks fizzled out early on Sunday.
Hundreds of thousands of people celebrated in sub-zero temperatures around Berlin's Brandenburg Gate, while thousands braved the cold and the numerous police controls to see in the New Year in Moscow's Red Square.
George Bush, the US president, announced his resolutions for the year ahead of the celebrations there: to work for peace and prosperity and, in the short term, to watch a bit of American college football.
Trent Duffy, the White House's deputy spokesman, said: "The president's New Year resolutions: to work tirelessly for peace abroad and prosperity at home."
Talabani hopes the government
will tackle areas of priority
In Baghdad, Jalal Talabani, the Iraqi president, said he hoped a new government of national unity would help to improve public services and defeat the insurgency in 2006.
"Problems of lack of security, electricity and water persist and I hope they will be areas of priority for the new government, which we hope will be one of national unity," Talabani said on Iraqi television.
In Israel, young people were determined to celebrate the New Year despite the disapproval of religious authorities who regard it as a Christian festival and a nationwide alert after a truce by Palestinian resistance groups had expired.
Israeli television and public radio reported 50 security alerts, about 10 of them concrete, about attacks being plotted by Palestinian armed groups to mark the holidays.
Two Palestinians were killed in the evening by Israeli fire in the northern Gaza Strip.
Palestinians buried two men killed
by Israeli troops in the Gaza Strip
However, flamboyant celebrating was not on the agenda in Lebanon, still living in the shadow of the latest assassination of an anti-Syrian political figure, the newspaper director Gebran Tueini.
Earlier in Sydney, Australia, 1700 police patrolled the streets and beaches to prevent a possible repeat of suburban race riots there in December.
Sydney's landmark Opera House was illuminated at midnight by a pyrotechnical display said to be the most spectacular ever seen in Australia's largest city.
Australia has 900 troops in Iraq and the government has warned repeatedly of attacks on home soil, but about one million people turned out in one of the first cities to leave 2005 and its violence behind.
In Beijing, bells and drums were sounded 108 times at midnight (1600 GMT) to mark an auspicious start to the year, signifying the elimination of worldly troubles in accordance with Buddhist tradition.
The authorities in Indonesia - already on high alert for possible attacks by extremists during the New Year period - fanned out in restive Central Sulawesi province after a bombing in a crowded market on Saturday left eight people dead.
The festive mood across much of the region contrasted with last year, when prayer vigils and fundraising events replaced jubilant blow-out bashes in the wake of the devastating December 2004 Indian Ocean tsunami.
In the United States, hundreds of thousands of partygoers flocked to New York's Times Square to remember the victims of Hurricane Katrina and salute relief workers toiling to clean up New Orleans, ravaged by the August storm.
In Africa, thousands of Kenyan prisoners decided to skip a meal on New Year's day to save money to help millions facing severe food shortages.