Thousands of police including increased numbers of firearms officers will be on duty as the capital ushers in the New Year tonight.
Scotland Yard said there will be around 3,000 officers across central London as mayor Boris Johnson's fireworks display with Unicef brings in 2016.
Metropolitan Police spokeswoman Superintendent Jo Edwards said: "New Year's Eve is a major celebration in the diary and the Met has been working with colleagues to ensure celebrations run smoothly and the event is safe and enjoyable for everyone who attends.
"Our policing plan remains under constant review and the public can expect to see additional police officers in central London, which includes an increased number of firearms officers. Our plans are purely precautionary and not as a result of any specific intelligence."
The event takes place as the New Year's Eve fireworks display in Brussels is cancelled because of threats of an extremist attack.
Brussels mayor Yvan Mayeur said the decision was taken on Wednesday evening after consultation with government officials.
Last December 31, 100,000 people turned out in the Belgian capital to ring in the new year. Brussels was home to four of the radical Islamic attackers who killed 130 people in Paris on November 13.
The Metropolitan Police said it had been working closely with the mayor's office, British Transport Police (BTP), Westminster City Council and others to ensure the event runs smoothly.
The mayor's fireworks display is ticketed for the second year and has sold out.
A police spokeswoman said: "If you do not have a ticket, entry will not be permitted, so the advice from the Met is to watch the spectacle from the comfort of your home. Alternatively you can see in the New Year at one of the hundreds of other celebrations taking place in restaurants, bars, pubs and clubs across the capital."
Superintendent Andy Morgan, silver commander for BTP, said: "New Year's Eve will undoubtedly be one of the busiest nights of the year for the emergency services and we will have officers on the ground at train and Tube stations across London.
"In order to provide further reassurance to everyone, we will also be extending our regular armed patrols and specialist support beyond normal hours.
"We would encourage everyone to enjoy their evening and to travel home safely, making sure you have your travel arrangements in place and know when your last train home is."
On New Year's Day, more than 8,500 performers representing 20 countries will take part in an annual parade through London. The event, which includes marching bands, cheerleaders, clowns and acrobats, kicks off in Piccadilly and finishes in Parliament Square, taking in Lower Regent Street, Pall Mall, Trafalgar Square and Whitehall.