While the prime minister said people should continue with their plans to celebrate, he asked people to mitigate risks by taking precautions.
"I think everybody should enjoy New Year but in a cautious and sensible way," said the prime minister.
"Take a test, ventilation, think about others — but above all, get a booster."
However, Johnson has been criticised over his emphasis on testing given widespread reports of shortages in PCRs and lateral flow devices.
The UK Health Security Agency (UKHSA) has cited “exceptionally high demand” as the cause of the shortages.
"We encourage people to revisit the site every few hours if they are unable to order tests as more will become available – and to please ensure they are making use of any tests they already have at home before ordering or collecting more," a spokesperson said.
Johnson has also warned that, despite the fact that Omicron appears to be less severe than previous strains of the virus, cases continued to rise and people are still being admitted to hospital.
“According to some of the surveys I’ve seen, 90% of the patients in ICU are people who are not boosted.
"So, think about that. Think about the risk you’re running with your own health if you fail to get a booster.”
Adding: “We’re looking at the data and what we’re seeing is that we’ve got cases certainly going up, we’ve got a lot of cases of Omicron."
Johnson's rhetoric strikes a different tone to guidance and restrictions in devolved administrations in Scotland, Wales, and Northern Ireland who have all introduced new measures in response to the new variant.
Scotland's world famous Hogmanay celebrations have been cancelled, and nightclubs have been ordered to close for at least three weeks from 27 December.
Scottish first minister Nicola Sturgeon has also urged the public to limit celebrations to three households.
Regarding testing, Sturgeon on Wednesday said that testing will be prioritised for essential workers as sampling processing capacity is “under pressure”.
She told the Scottish Parliament that “there were steps taken to constrain demand in England last night (Tuesday)”, meaning no slots were available to book at physical test sites but “an administrative error” also restricted appointments at sites in Scotland, Wales and Northern Ireland.
Meanwhile in Wales, the rule of six in hospitality and the banning of large events with more than 50 people has been introduced, with nightclubs also closed.
Welsh first minister Mark Drakeford warned the Welsh public they were "facing a very serious situation in Wales". Similar measures have been taken in Northern Ireland.
When asked why England was taking a different route, the prime minister said he had looked at risks and the data.
“I think that we’ve looked at the balance of the risks together, we generally concert our strategies together, we see the data showing that, yes, the cases are rising and, yes, hospitalisations are rising, but what is making a huge difference is the level of booster resistance or level of vaccine-induced resistance in the population," he said.
On Tuesday, regius professor of medicine at the University of Oxford, Sir John Bell, said COVID was "not the same disease" as it was and that Omicron seems to be "less severe" and people spend "a relatively short time in hospital".
He also said high numbers of deaths from the virus are "now history".
The UK recorded its highest ever number of new COVID cases in a 24 hour period on Tuesday, reporting 129,471 and 17 deaths.
Watch: COVID-19: Boris Johnson says 'up to 90%' in intensive care have not had a booster and urges people to get jabbed