Iran Press/ Europe: Johnson said the steps were necessary to avoid the medical and moral disaster of the National Health Service NHS being overwhelmed.
Non-essential shops and hospitality will have to close for four weeks on Thursday, he said.
But unlike the restrictions in spring, schools, colleges, and universities will be allowed to stay open.
After 2 December, the restrictions would be eased and regions would go back to the tiered system, he said.
Johnson said: "Christmas is going to be different this year, perhaps very different, but it's my sincere hope and belief that by taking tough action now we can allow families across the country to be together."
The prime minister told a Downing Street news conference that he was "truly, truly sorry" for the impact on businesses, but said the furlough system paying 80% of employee wages will be extended through November.
He said hospitals even in the south-west of England, where cases are among the lowest, will run out of capacity in weeks.
The UK recorded another 21,915 confirmed coronavirus cases on Saturday, bringing the total since the pandemic began to 1,011,660.
Another 326 people were reported to have died within 28 days of a positive test.
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