England will enter a month-long lockdown from Thursday, Boris Johnson has announced.
Until 2 December, people in England will only be allowed to leave their homes for specific reasons, such as education, work or food shopping.
Mr Johnson, speaking at a Downing Street news conference on Saturday evening, said there was "no alternative" to a second period of national lockdown restrictions.
He said that "no responsible prime minister" could ignore the rising number of coronavirus infections across England.
Mr Johnson warned of a greater number of COVID-19 deaths this winter than during the first wave of the pandemic, in the spring, without tougher measures.
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Schools, colleges and universities will remain open while those who cannot work from home, such as construction or manufacturing workers, will be encouraged to continue going to their workplaces.
Pubs, bars and restaurants will close across the country, although they will be able to offer takeaway and delivery services.
Non-essential shops, hairdressers and leisure and entertainment venues will also be shut.
The prime minister said the furlough scheme, which has seen the government pay a proportion of peoples' wages during the COVID-19 crisis but was due to end on Saturday, would now be extended through November.
Different households will be banned from mixing, although support bubbles and childcare bubbles will remain and children will still be able to move between homes if their parents are separated.
Gyms will be shut but people can continue to exercise for unlimited periods outdoors, either with people from their own households or on a one-to-one basis with one person from another household.
People will be able to travel internationally for work, but won't be allowed to go abroad for holidays.
Premier League football and other elite sports will be allowed to continue, due to the testing regimes in place for professional sportspeople, but amateur sports will be put on hold.
MPs are expected to vote on the fresh measures on Wednesday.
Mr Johnson has taken the action after warnings from the government's scientific advisers that hospitals could run out of beds by early December without new measures.
Until now, the government has been pursuing a localised approach to COVID-19 restrictions, with England divided into three levels of measures, depending on local infection rates.
The government's aim is that, after the month-long period of tougher national measures, different parts of the country will be released back into the existing three tiers, depending on regional transmission rates.
Earlier on Saturday, Mr Johnson's top ministers were briefed by the government's scientists prior to a remote cabinet meeting.
The prime minister also held talks with senior Conservative MPs.
