Celebrations have continued around the world as cities including Paris and Berlin welcome the year 2020 and the beginning of a new decade.
Among the first major centres entering 2020 was Australia's largest city of Sydney, where fireworks lit up the skyline.
But the celebrations were mired in controversy due to the ongoing bushfires ravaging parts of the country.
There were doubts as to whether the impressive display to ring in the new year would go ahead because of the devastation caused by the flames, which have forced hundreds from their homes in New South Wales .
Prime Minister Scott Morrison was sharply criticised by activists and some of his constituents for the lavish firework display.
"The arrogance of this government is beyond belief," activist Erik Standing Bear wrote in a Facebook post.
"Another firefighter has lost his life. Several people are missing but government and certain people need to have their party. Disgraceful."
More than a million people still descended on Sydney Harbour for the traditional event, having been granted an exemption from a fireworks ban to prevent further wildfires.
The celebrations in Sydney, which is the capital of New South Wales, were expected to generate some £69m for the regional economy - but many still called for them to be cancelled.
Responding to critics, the city mayor Clover Moore said planning for the fireworks began 15 months ago and most of the budget had already been allocated.
Some one billion people worldwide were thought to have watched the Sydney event, which came two hours after an impressive display in Auckland, New Zealand.
Half a tonne of fireworks burst from the Sky Tower above the city centre, bringing to an end a year that has not been short on tragedy for the small nation.
Back in March, a gunman killed 51 people and injured dozens of people at two mosques in Christchurch - and in December at least 19 were killed when a volcano erupted on White Island .
Later there were impressive displays in the North Korean capital Pyongyang and Seoul in South Korea, with the latter seeing thousands gather in the cold downtown streets ahead of a traditional bell-tolling ceremony near City Hall.
Fireworks also drew large crowds in Tokyo, including at the city's Disneyland theme park, as locals prepare for an exciting year that will see them welcome visitors from all over the world for the 2020 Olympics this summer.
Stalls at Zojoji Temple sold sweet rice wine, fried noodles and candied apples, as well as little amulets in the shape of mice, the zodiac animal for 2020. The Asian zodiac begins with the Year of the Mouse so it's associated with starting anew.
Hong Kong opted for a more modest light show, accompanied by a cinematic soundtrack, as the city bid farewell to a year dominated by mass protests against the government .
Authorities deployed 6,000 police officers on the streets of the Chinese-run former British colony, where the usual fireworks display was cancelled.
Leader Carrie Lam appealed for calm and reconciliation in her New Year's Eve video message, with protesters seen forming human chains urging people not to give up the fight for democracy in 2020.
One was seen holding a banner reading: "Never forget. Never forgive."
Russia began the world's longest continuous New Year's Eve with fireworks and a message from President Vladimir Putin urging them to work together in 2020.
Mr Putin made the call in a short speech broadcast on television just before the stroke of midnight in each of Russia's 11 time zones.
He said the country was "living in turbulent, dynamic and controversial times, but we can and should do everything for Russia to develop successfully".
But one thing was missing in Moscow - a picturesque layer of snow. Due to an unusually warm December, temperatures in central Moscow were just above freezing as midnight approached.
The New Year's Eve celebrations in Samoa were more sombre than usual, though fireworks erupted at midnight from Mount Vaea, overlooking the capital, Apia.
A measles epidemic claimed 81 lives in Samoa this year, mostly children under five.
Meanwhile in the UK, Londoners have started making their way to the banks of the River Thames to find a spot to watch a spectacular fireworks display launched from the London Eye and a series of barges near Parliament.
Speaking to Sky News ahead of the celebrations, London mayor Sadiq Khan said: "My hand is on my heart, they'll be the best fireworks that London has ever seen. It's going to be amazing."
He added that there was a "football theme" for the celebrations due to London hosting seven football games in 2020, including the Euro 2020 final.
He said: "We've got everything - we've got great music from London artists including Stormzy, Wiley, Bastille, but also those who are football fans will recognise one or two other tracks."
In Indonesia, tens of thousands of revelers in the country's capital of Jakarta were caught in torrential rains as they waited for New Year's Eve celebrations, while others were wary of an active volcano.
Dubai welcomed 2020 with a bang as fireworks burst from the world's tallest building, the Burj Khalifa.
Fireworks lit up the sky for nearly 10 minutes as hundreds of thousands gathered downtown to watch the spectacular display. The New Year's Eve display at the 828-metre-tall (2,176ft) tall skyscraper is just one of seven different firework displays across the emirate.
In South Africa, thousands of people gathered at Cape Town's waterfront for music, dancing and fireworks.
Previously, residents of Johannesburg's poor Hillbrow neighbourhood would celebrate by tossing furniture and appliances from balconies of apartment buildings but, following police warnings, it appears this tradition has declined.
President Cyril Ramaphosa said: "While our economy created jobs, these have not been nearly enough to stop the rise in unemployment or the deepening of poverty."
In Rome, Pope Francis, 83, took a stroll to admire the Nativity scene in St Peter's Square.
There were shouts of "Pope" Pope!" and "Happy New Year" from the crowd as people rushed to see him or held babies in his path so he would pat their heads.
At a New Year's Eve Vespers service in St Peter's Basilica, he urged people to practice more solidarity and to "build bridges, not walls".