Thousands gathered on the streets of Edinburgh for the sold-out world-famous Hogmanay Celebrations which will see Scots favourite Paolo Nutini headline The Concert In The Gardens.
The world-renowned street party will also see performances from The Charlatans, Fatherson and Be Charlotte.
Four firework displays were due to be held rising to the crescendo of the spectacular Midnight Moment display from the ramparts of Edinburgh Castle, Princes Street Gardens and Calton Hill which will also include a laser show this year.
Thousands of party-goers will join hands to sing the world's largest rendition of Auld Lang Syne at the stroke of midnight, with images being beamed around the globe.
There was a huge police presence on the streets of London as spectators from nearly 100 countries flocked to the Thames to watch the night sky light up as Big Ben struck midnight.
With memories of the lethal Berlin lorry truck attack still fresh, London mayor Sadiq Khan assured crowds the capital was "as safe as it possibly can be".
Mr Khan said the mood on the streets was "upbeat", adding it was "really important we don't allow terrorists to disrupt our celebrations on this New Year's Eve".
Around 3,000 officers were on duty within and outside ticketed areas, while armed police were also set to be a fixture on the capital's Tube trains as they travel between jobs in a move aimed at reassuring passengers.
Tonga welcomed in 2017 at 10am GMT today – a full three hours before it reaches Australia, which is often associated with being the first to enter a New Year due to its famous Sydney Harbour fireworks display.
Tourists and French revellers swarmed along Paris' illuminated Champs Elysees Avenue on a frosty night, admiring the laser display from the Arc de Triomphe and lines of trees sparkling with lights.
"It's so magical to be here in Paris, on what people say is the world's most beautiful avenue," said Maureen O'Reilly, 42, a visitor from Belfast, Northern Ireland.
"At times like this, I do think about all those terrible things in Aleppo and how lucky we are here in Europe despite everything."
Tens of thousands of merrymakers converged on Times Square on Saturday evening, hours before the giant New Year's Eve ball makes its midnight descent, a century-old New York tradition unfolding this year under an unprecedented blanket of security.
As many as 2 million people, surrounded by a ring of 40-ton sand trucks and some 7,000 police, are expected to gather in the "Crossroads of the World" to watch the glittering sphere complete its midnight drop, marking the beginning of 2017.
The last place or places to receive 2017 will be the tiny outlying islands of the US.
Sydney sent up a dazzling tribute to 2016's fallen icons with a New Year's Eve fireworks display honouring the late singer David Bowie and late actor Gene Wilder, becoming the first major city to bid a bittersweet adieu to a turbulent year.
The glittering display over Sydney's famed harbour and bridge featured Saturn and star-shaped fireworks set to "Space Oddity," the classic song by Bowie one of the many beloved entertainers who died in 2016.
"This year, sadly, we saw the loss of many music and entertainment legends around the world," fireworks show co-producer Catherine Flanagan said.
"So celebrating their music as part of Sydney New Year's Eve fireworks displays is an opportunity to reflect on the year that has been and what the future may hold."
More than 300,000 visitors are expected to descend on Las Vegas for an extravagant New Year's Eve celebration.
Meanwhile, Pope Francis has called on the faithful to help young people find a place in society, noting the paradox of "a culture that idolises youth" and yet has made no place for the young.
Francis said during vespers marking New Year's Eve that young people have been "pushed to the margins of public life, forcing them to migrate or to beg for jobs that no longer exist, or fail to promise them a future."
A worker arrangers rows of freshly roasted pigs, known locally as "lechon", at a store in Manila, Philippines
Second last will be American Samoa at 11am – just 558 miles from Tonga, where locals and visitors were celebrating a full 25 hours before.
Watch each country bring in the new year here as we follow the start of 2017 around the world.
The Philippines' notorious tradition of dangerous New Year's Eve celebrations persisted after President Rodrigo Duterte delayed to next year his ban on the use of powerful firecrackers, often worsened by celebratory gunfire.
Tonga was the first at 10am GMT, followed by New Zealand at 11am, Australia, Japan and South Korea.
At around 3.30pm GMT North Korea rang in the new year followed by China, the Phillipines, and most of Indonesia.
As we Brits headed into the evening people in Bangalesh, Nepal, India and Pakistan were welcoming in their 2017, before countries like Russia, Greece and Germany took their turn from 9pm onwards.
Following the UK at midnight will be Brazil at around 2am, the USA at 3.30am, and finally its outlying islands at 12 noon tomorrow.
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