The Pacific nation of Kiribati is the first to welcome in 2024.
New Zealand, Tonga and Samoa will be next, with many millions of people expected to take part in celebrations around the world in the coming hours.
Huge crowds are gathering in Sydney in Australia for one of the world's most spectacular New Year's fireworks displays.
Just before midnight there - 13:00 GMT - eight tonnes of pyrotechnics will be launched from two of Australia's most recognisable landmarks - the Harbour Bridge and the Opera House.
The last place will be Baker Island - only 650 miles away from Kiribati, but 26 hours behind, due to time zones quirk.
More than 100,000 people are expected to watch London's sold-out New Year's Eve display in person, with millions more tuning in online or on BBC One
