Australia, New Zealand, Russia, Japan and Thailand are among the countries to have welcomed in 2016 while Dubai went ahead with its spectacular fireworks display as planned while fire crews battled a blaze that engulfed a nearby skyscraper.
t was not immediately clear what caused the fire, which ran up at least 20 storeys of the building near the Burj Khalifa, the world's tallest skyscraper at 828m (905 yards).
Burning debris rained down from the building as firefighters raced to the scene. Injuries were reported but despite the scale of the task facing the emirate's firefighters, the festivities continued nearby as scheduled at midnight.
Earlier New Zealand counted down the seconds to midnight with a giant digital clock on Auckland's Sky Tower as it become the first nation with a sizeable population to welcome in the new year.
Horns blared and crowds cheered as the tower was then lit up with fireworks, with colours shifting from green to red to white.
In Australia, simultaneous fireworks displays erupted along Sydney's famed harbour, where people crowded onto balconies, into waterside parks and onto boats as they jockeyed for the best view, clinking glasses and whooping with joy as the first pyrotechnics exploded.
More than one million people were expected to watch the glittery display, featuring a multicoloured firework "waterfall" cascading off the Harbour Bridge and effects in the shapes of butterflies, octopuses and flowers.
Australian officials, struggling to contain the threat from home-grown extremists, encouraged revellers to enjoy the evening and assured them that thousands of extra police were patrolling major cities.
"Don't change your way of life," Melbourne lord mayor Robert Doyle urged residents of his city. "Don't let events from around the world challenge the way that we live."
New Year's Eve is Japan's biggest holiday, and millions crammed into trains to flee the cities for their home towns to slurp down bowls of noodles, symbolising longevity, while watching the annual Red and White NHK song competition.
Tokyo was on special alert for security issues this year, with posters in underground stations and other public spaces warning people to keep their eyes open for suspicious packages or activities.
South Koreans traditionally mark New Year's Eve with bell ringing ceremonies, fireworks and outdoor music and dance performances.
Thousands of people, including North Korean refugees, were expected to gather at a town near the border with rival North Korea to watch one of the ceremonies and wish for peaceful Korean unification.
North Korea was expected to mark the new year with a speech by leader Kim Jong Un, which outside observers use to pore over for insight on the reclusive country's policy direction.
Meanwhile China held an official New Year's Eve celebration near Beijing's Forbidden City.
For security reasons, Shanghai closed underground stations near the scenic waterfront Bund because of a stampede last New Year's Eve that killed 36 people and blemished the image of China's most prosperous and modern metropolis.
Security is a big concern in many cities around the world this New Year's Eve.
In the Thai capital Bangkok, police-flanked partygoers rang in the new year at the site of a deadly bombing that took place just months ago.
In Paris, residents recovering from their city's own deadly attacks will enjoy scaled-back celebrations.
And in the Belgian capital Brussels, 2016 will be rung in without the customary fireworks display and street party.
The festivities were cancelled by mayor Yvan Mayeur, who said on Wednesday evening it would have been impossible to administer adequate security checks to all of the 100,000 people expected to attend.
On Thursday morning, forklifts and trucks removed generators and other equipment from the Place de Brouckere, the broad square in central Brussels where the fireworks show was supposed to happen. Some people said they understood the cancellation, others called it knuckling under to the extremist threat.
"I think it is a good and wise decision," said Koen Vandaele, a Brussels resident. "There could be a lot of confusion if the fireworks started" and there was a fresh attack.
"I think it is backing down to the threat to terrorism," disagreed Ken Kinsella, another Brussels resident. "There is no point in running away from it so I think they should have gone ahead with it."