Thousands of people lined the Thames as London kicked off the new decade to the roar of football anthems such as Three Lions with the festivities providing a prelude to the Euro 2020 football tournament.
Sadiq Khan, the Mayor of London, had promised the display - which also featured music from Stormzy, Wiley and Bastille - would be the best the capital "has ever seen".
Big Ben rang out 12 times to mark the start of the new year despite the bell falling mostly silent in 2019 while renovation work is completed.
London's annual New Year's Eve fireworks display was sold out, with around 100,000 revellers packed into the streets around Victoria Embankment.
Around 2,000 fireworks set off during the display were fired from the London Eye, with the remainder coming from barges moored in a central location along the River Thames.
The show celebrated London's role in hosting this summer's international football tournament, which will take place in countries across the continent rather than being hosted by a single nation - and will see the capital host more fixtures than any other city.
Seven of the competition's matches are set to be played in the capital, with Wembley Stadium scheduled to host the final and semi-finals.
"Footballs coming home" blared out as the Baddiel, Skinner and Lightning Seeds' favourite accompanied the spectacular show, followed by The White Stripes' Seven Nation Army and classical hit Nessun Dorma.
The 1990 World Cup theme was played as the city welcomed in 2020 with a dazzling riverside fireworks display, featuring more than 12,000 fireworks.
Speaking in the city centre ahead of the celebrations on Tuesday night, Mr Khan told the PA news agency the "world" will be watching the display, and he hoped it would show London was a "global city".
He said: "Fairly or unfairly, people around the world saw the Brexit referendum vote as the UK somehow turning its back on the rest of the world, including Europe.
"The fear was, we would become insular, inward-looking, and what I'm keen to show is the opposite.
"Yes we may be leaving the EU, but very much as a city we are still a European global city. We will continue to be open to people's trade and ideas."
In Edinburgh, Auld Lang Syne rang out to begin the year, sung by revellers packing the Scottish capital's streets for a Hogmanay party that had included a night of music, parties and more than 3,600 fireworks let off from Edinburgh castle.
Around 100,000 visitors were expected to attend the event, according to organisers who billed the celebrations as the UK's biggest New Year's Eve street party.
The festivities began in the city on Monday as around 40,000 people joined a torchlit procession which culminated in them forming the shape of two humans reaching out a "hand of friendship".
Large pyrotechnics shows also took place in cities across the country including Manchester, Cardiff, Newcastle, Inverness and Nottingham.
You can see pictures from all the celebrations in our gallery here.
For nearly 10 minutes, fireworks lit up the sky over Dubai's Burj Khalifa, the world's tallest building, as hundreds of thousands gathered downtown to watch the spectacular display.
The New Year's Eve display at the 2,716-foot-tall skyscraper was just one of seven different fireworks shows across the emirate. Tourists, especially from Europe and Russia, flock to the sunny beaches of Dubai at this time of year to escape the cold, dark winter.
To keep the massive crowds safe, police created walkways around the Burj Khalifa tower for male-only groups to separate them from families and women.
Dubai this year will be hosting Expo 2020, a world fair that brings the most cutting-edge and futuristic technologies.
Russians 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 the coming year.
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. The recorded message was followed by an image of the Kremlin Clock and the sound of its chimes. State TV showed footage of extensive festive fireworks in cities of the Far East.
But one holiday tradition was missing in Moscow this year - a picturesque layer of snow. The Russian capital has had an unusually warm December and temperatures in central Moscow as midnight approached were just above freezing.
Indian festivities dampened by protests
Thousands of Indians ushered in the year by demonstrating against a citizenship law they say will discriminate against Muslims and chip away at India's secular constitution.
Demonstrations were planned in New Delhi, in the grip of its second coldest winter in more than a century, as well as Mumbai and other cities, despite Prime Minister Narendra Modi's attempts to dampen demonstrations that have run for nearly three weeks.
Irshad Alam, a 25-year-old resident of the Shaheen Bagh area of New Delhi, stood with his 1-year-old in his arm and his wife by his side. He said he had been participating in the protest every day.
"It’s freezing here," he said. "But we are still here because we care about this movement."
Beijing pledged to to 'seize the day'
President Xi Jinping delivered a New Year speech in Beijing to ring in 2020, pledging to achieve the first centenary goal of building a moderately prosperous society in all respects in the "milestone" year.
"Let's seize the day and live it to the full," Xi said, as celebrations were well underway including a spectacular party at Shougang Industrial Park, one of the venues for the Beijing 2022 Olympics.
Rain couldn't stop play in Indonesia
Tens of thousands of revellers in Indonesia's capital of Jakarta were soaked by torrential rains as they waited for New Year's Eve fireworks.
Festive events along coastal areas near the Sunda Strait were dampened by a possible larger eruption of Anak Krakatau, an island volcano that erupted last year just ahead of Christmas Day, triggering a tsunami that killed more than 430 people.
The country's volcanology agency has warned locals and tourists to stay 2 kilometers (1.3 miles) from the volcano's crater following an eruption Tuesday that blasted ash and debris up to 2,000 meters (6,560 feet) into the air.
Kuala Lumpur lights up the night as Singapore sparkles
Pro-democracy chants in Hong Kong as fireworks cancelled
Pro-democracy protesters and revellers flocked to sites across Hong Kong to usher in 2020, but the semi-autonomous Chinese city had toned down its New Year's celebrations amid the months-long demonstrations.
A fireworks display that traditionally lights up Victoria Harbor was cancelled amid safety concerns. Despite this, thousands welcomed 2020 on its neon-lit promenades and many broke into pro-democracy chants shortly after the countdown to midnight.
Instead of fireworks, a "Symphony of Lights" took place, involving projections on the city's tallest skyscrapers, while smaller-scale pyrotechnics were launched from waterfront rooftops.
Australia sees in the new roaring 20s
Australia ushered in the New Year with a huge fireworks display in Sydney, despite the calls to cancel the event as devastating bushfires raged across the country.
A petition to cancel the event out of respect for fire victims attracted more than 280,000 signatures. Fireworks displays were scrapped in Australia's capital, Canberra, and Sydney's western suburbs due to elevated fire danger and extreme weather conditions.
Critics had wanted Sydney to use the Aus $6.5 million ($4.5 million) spent on the display to fight bushfires ringing the city, but officials said the event was worth Aus $130 million to the economy and cancelling it would not have helped those impacted by the fires.
More than 100,000 fireworks lit up the skyline for the hundreds of thousands of spectators thronging the city centre.
Crowds were warned to take care as strong winds gusted in the harbour, forcing the cancellation of a boat display that would have blasted water into the sky.
Japan's new era celebrates its first New Year's
People flocked to temples and shrines in Japan, offering incense with their prayers to celebrate the passing of a year and the first New Year's Eve of the Reiwa era.
Under Japan's old-style calendar, linked to emperors' rules, Reiwa started in May, after Emperor Akihito stepped down and his son Naruhito became emperor. Although Reiwa is entering its second year with 2020, Jan 1 still marks Reiwa's first New Year's, the most important holiday in Japan.
The first year of the new decade will see Tokyo host the 2020 Olympics, an event that is creating much anticipation for the capital and the entire nation.
It's officially 2020 now in New Zealand
As the most populated city in New Zealand, Auckland always puts on a good show and the Sky Tower display was spectacular as half a ton of fireworks burst from the landmark towering over the city centre.
Thousands gathered around the tower, where - for the first time - lasers and animations accompanied the fireworks display.
South Korea and Samoa have started the party
Thousands of South Koreans filled the downtown streets in Seoul ahead of a traditional bell-tolling ceremony near City Hall. Dignitaries picked to ring the old Bosingak bell at midnight included South Korean Major League Baseball pitcher Hyun-Jin Ryu and Pengsoo, a giant penguin character with a gruff voice and blunt personality that emerged as one of the country's biggest TV stars in 2019.
In Samoa, fireworks erupted at midnight from Mount Vaea, overlooking the capital, Apia. The Pacific island nation of Kiribati was also one of the first countries to welcome the new decade. The nation's 3,200 coral atolls are strewn more than 3 million square miles, straddling the equator.