Here's a look at how people are ushering in the new year across Asia, Europe, Africa and the Americas as the clock ticks past midnight.
North Korea Leader Kim Jong Un will keep North Korea watchers busy on New Year's Day when he is expected to give his annual address laying out the country's priorities for the year ahead. The speech is often the best gauge of what the North Korean leadership is focused on and what tone it will take in its dealings with the outside world.
Kim's speech will be parsed carefully for clues about his thinking on denuclearization talks with Washington and a second summit with US President Donald Trump, relations with South Korea, and North Korea's efforts to get out from under international sanctions as it tries to build its domestic economy.
In his New Year's speech this past year, Kim proposed talks with South Korea to reduce tensions and said the North would be willing to participate in South Korea's Winter Olympics, setting off a series of summits with the South and the United States.
South Korea After an eventful year that saw three inter-Korean summits and the easing of tensions over North Korea's nuclear programme, South Koreans enter 2019 with hopes that the hard-won detente will expand into a stable peace.
Thousands of South Koreans were expected to fill the streets of the capital, Seoul, for a traditional bell-tolling ceremony near City Hall to usher in the new year.
Dignitaries picked to ring the old Bosingak bell at midnight include famous surgeon Lee Guk-jong, who successfully operated on a North Korean soldier who escaped to South Korea in 2017 in a hail of bullets fired by his comrades.
Elsewhere, about 10,000 people were expected to attend the tolling of a "peace bell" at Imjingak, a pavilion near the border with North Korea.
New Zealand In Auckland, New Zealand's biggest city, tens of thousands gathered around Sky Tower as fireworks exploded from the top of the 328-metre structure.
Across the southern hemisphere nation, thousands took to beaches and streets, becoming the first major nation in the world to usher in 2019.
Fireworks boomed and crackled above city centres and harbours.
Australia An estimated one million people crowded Sydney Harbor as Australia's largest city rang in the new year with a spectacular, soul-tinged fireworks celebration.
One of the most complex displays in Australia's history included gold, purple and silver fireworks pulsating to the tune of "(You Make Me Feel Like) A Natural Woman", made famous by Aretha Franklin, who died in August. The show used 8.5 tonnes of fireworks and featured more than 100,000 pyrotechnic effects, the city's biggest-ever fireworks display.
Earlier, a thunderstorm drenched tens of thousands of people as they gathered for the traditional display, creating a show of its own with dozens of lightning strikes.
More than one billion people around the world were expected to watch the fireworks on television.
In Melbourne, 14 tonnes of fireworks deployed on the ground and on roofs of 22 buildings produced special effects including flying dragons. In Brisbane, an estimated 85,000 people watched as fireworks exploded from five barges moored on the Brisbane River.
Philippines Dozens of people have been injured by firecrackers ahead of New Year's Eve when many across the Philippines set off powerful firecrackers in one of Asia's most violent celebrations despite a government scare campaign and threats of arrests.
The Department of Health said it has recorded more than 50 firecracker-caused injuries in the last 10 days, which is expected to increase overnight when Filipinos usher in 2019 with a bang.
Although still a concern, the figure is significantly lower than a year ago, partly because fewer Filipinos have purchased firecrackers due to hard economic times.
Officials have urged centralised fireworks displays to discourage wild and sometimes fatal merry-making. The notorious tradition, worsened by celebratory gunfire that turned deadly, stems from a Chinese-influenced belief that noise drives away evil and misfortune.
China New Year's Eve isn't celebrated that widely in mainland China, where the Lunar New Year in February is a more important holiday, but countdown events were being held in major cities and some of the faithful headed to Buddhist temples for bell-ringing and prayers.
The city of Beijing was holding a gala with VIP guests at the main site of the 2008 Summer Olympics. The event looked ahead to the 2022 Winter Games, which also will be held in the Chinese capital.
Additional police were deployed in parts of Shanghai, where a New Year's Eve stampede in 2014 killed 36 people. In Beijing, outdoor revelers had to brave temperatures well below freezing.
President Xi Jinping, in a message broadcast at the top of the evening news, outlined the country's achievements over the past year and said that by hosting a series of multinational meetings in 2018, "we have put forward China's proposals and sent out China's voice."
In Hong Kong, festive lights on the city's iconic skyscrapers provided the backdrop for a fireworks, music and light show over Victoria Harbor on a chilly evening. About 300,000 people were expected to line the waterfront.
Thailand While many celebrate New Year's Eve with fireworks, hundreds of Thais travelled to Takien Temple in a suburb of Bangkok to lie inside coffins for traditional funeral rituals. Participants believe the ceremony - symbolising death and rebirth - helps rid them of bad luck and allows them to be born again for a fresh start in the new year.
Participants held flowers and incense in their hands as monks covered them with pink sheets and chanted prayers for the dead.
"It wasn't scary or anything. It is our belief that it will help us get rid of bad luck and bring good fortune to our life," said Busaba Yookong, who came to the temple with her family.
Bangkok is filled with modern glitzy malls and high-rise buildings, but superstitious beliefs still hold sway in many aspects of Thai society.
Britain Cities across Europe have also welcomed 2019 with a series of firework displays, including one in London that was dedicated to the EU citizens living in the British capital.
The words "London is open" were spoken in seven languages as the fireworks at the London Eye ferris wheel went off, while the soundtrack included the songs "We Are Your Friends", "Stay" and "Don't Leave Me Alone".
"By paying tribute to our close relationship with Europe as we welcome in the New Year tonight, we will once again show the world that London will always be open," Mayor Sadiq Khan said.
The London mayor has been vocal about how Britain's planned departure from the European Union on March 29 will affect his city.
From Berlin to Athens Fireworks also lit up the skies over the Brandenburg Gate in the German capital, Berlin, as well the Arc de Triomphe in Paris, where the names of this year's victorious French football World Cup-winning team were projected onto the landmark.
Sweden greeted the New Year with its annual tradition of a reading of Alfred Lord Tennyson's poem "Ring Out Wild Bells", read this year by actor Mikael Persbrandt.
In the Russian capital, Moscow, the bells in the Kremlin's Spasskaya Tower rang out, but the party mood was dampened by a gas explosion at an apartment building in the southern city of Magnitogorsk. Dozens of people are still missing.
In Athens, where fireworks went off above the Acropolis despite pouring rain, Greek Prime Minister Alexis Tsipras promised that "2019 will be a year of rebirth for our country."
Greece, which has struggled with a financial crisis for the best part of a decade, officially exited its bailout programme in August.
United States Meanwhile, in the United States, celebrations were still gearing up. Snoop Dogg, Sting and Christina Aguilera will welcome 2019 in a packed Times Square along with revellers from around the world who come to see the traditional crystal ball drop.
Spectators are expected to start assembling early in the afternoon for the made-for-TV extravaganza.
The celebration will take place under tight security, with partygoers checked for weapons and then herded into pens, ringed by metal barricades, where they wait for the stroke of midnight.
Eleven journalists are set to press the button releasing the crystal ball, the New York Times reported, as part of an effort to recognise the erosion of press freedoms at home and abroad.
Los Angeles and Honolulu were to round out the US reverie.
Brazil Hundreds of thousands of people celebrated the arrival of the New Year in Rio de Janeiro with fireworks, music and dancing.
Locals and tourists mixed on the city's famous Copacabana beach to watch a 14-minute spectacle that saw several tonnes of fireworks fired into the air at midnight (02:00 GMT).
Before and afterwards there was music and dancing by bands and DJs including well-known guitarist and former culture minister Gilberto Gil and popular funk singer Ludmilla.
Latin America's largest country will undergo a radical change on New Year's Day, when far-right President Jair Bolsonaro is sworn in. - Aljazeera