The skies of the nation's capital were filled with colour as revellers gasped in awe during a New Year's fireworks spectacular dubbed the "best ever" by London Mayor Sadiq Khan .
The event sold out with more than 100,000 tickets being bought and the cutting-edge pyrotechnics show featured more than 12,000 fireworks.
And this year the event had a special theme as it looked ahead to the city hosting several key games in the Euro 2020 football tournament.
The London Mayor promised the "best fireworks London has ever seen" and that the capital would "project confidence" on the world stage.
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.
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"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.
"What tonight's fireworks are about is demonstrating our confidence.
"And it's really important that we show the world who will be watching our fireworks that we are a confident, global, outward-looking European city."
Around 2,000 of the 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, according to Darryl Fleming of Titanium Fireworks, who is display director for the show.
Visibility was good for the display, as New Year's Eve was cold but dry for many, with temperatures in Scotland and parts of northern England around 1C (33.8F) or 2C (35.6F), according to the Met Office .
There were patches of fog appearing across the UK, according to Met Office forecaster Greg Dewhurst, but this did not blight the displays in either London or Edinburgh.
The display was set to a soundtrack "inspired by London and Europe", according to a spokesperson for the mayor.
Thousands of people lined the Thames to the roar of football anthems such as Three Lions.
"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.
Big Ben's chimes sounded the start of the display, despite them being silent this year while renovation work is completed.
There was a football theme to the music, but also a London theme, with tracks by Grime stars Stormzy and Wiley as well as the band Bastille.
RnB star Craig David performed for the hour leading up to the fireworks.
Revellers were warned by the Local Government Association to avoid "cheap and dangerous" fake alcohol being sold by rogue traders ahead of the New Year celebrations.
Their warning follows multiple council seizures of counterfeit vodka from shops and storage facilities, the organisation added.
"Some counterfeit bottles of vodka are said to contain industrial strength levels of alcohol which can lead to vomiting, permanent blindness, kidney or liver problems and, in extreme cases, death," they said in a statement.
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.
