A total of 119,789 new daily cases as well as 147 new deaths were reported on Thursday, taking the total number of fatalities to 147,720.
It is the highest number of new cases since the pandemic first reached the UK in early 2020 and is the second consecutive day of record new cases.
About 1 in 45 people now have Covid-19 in England, official figures show. In Wales, the figure is 1 in 55 people, Northern Ireland is 1 in 50 and Scotland is 1 in 70. In London, 1 in 30 people have the disease.
A record 464,667 people tested positive for Covid-19 in England at least once in the week ended December 15, up 47 per cent on the previous week, Test and Trace figures released on Thursday showed.
But the number of patients in intensive care has not increased dramatically, a possible sign that Omicron is not as lethal as previous strains.
Three reports published in the last two days indicate those infected with the Omicron variant may be less likely to need hospital treatment, though they may be much more contagious.
“Cases of the variant continue to rise at an extraordinary rate — already surpassing the record daily number in the pandemic. Hospital admissions are increasing and we cannot risk the NHS being overwhelmed,” Health Secretary Sajid Javid said.
“This is early stage analysis and we continue to monitor the data hour by hour. It is still too early to determine next steps, so please stay cautious this Christmas and get your booster as soon as possible to protect yourself and your loved ones.”
The UK recorded more than 100,000 daily Covid-19 cases for the first time on Wednesday.
Despite the surge, UK Prime Minister Boris Johnson and Mr Javid have confirmed they will not introduce new restrictions before Christmas.
The devolved administrations in Scotland, Wales and Northern Ireland each announced new post-Christmas restrictions.
As the highly infectious Omicron mutation spreads through the UK, the government has focused efforts on delivering the vaccine booster to as many people as possible.
But more than six in 10 care-home staff in England have not received the booster.
About 37.6 per cent of staff in care homes for the elderly and 33.5 per cent of staff in homes for younger adults had received a booster as of December 19, the latest figures from NHS England show.
This leaves more than 340,000 staff who have not been recorded as having received a booster.