The government has announced that people in Leeds will be banned from meeting with other households from midnight tonight.
The new restrictions bring the city in line with rules in Bradford, Kirklees and Calderdale.
The health Secretary, Matt Hancock published a statement announcing the news, which said that the decisions to impose tougher measures had not been "taken lightly", and that restrictions will be kept "under review and in place no longer than they are necessary".
Leeds City Council leader Judith Blake said the city has been made an "area of intervention", while the leader for public health said the restrictions could last through winter.
The city council said there had been a "steep rise" in infections, with the rate at 98.5 per 100,000 people.
The move will have an impact on 780,000 people but some exemptions are expected, including for those with caring responsibilities.
People who live in Leeds and surrounding areas will not be allowed to gather in a private dwelling or garden with any other household unless in a support bubble.
Visitors from elsewhere will also not be allowed to gather with another household in a private dwelling or garden in these areas.
Ms Blake said the duration of the new measures "will depend on everyone playing their part".
"We are acutely aware that nobody wants to see further restrictions placed on life in Leeds and alongside our partners we have been doing absolutely everything within our power to avoid that," she said.
Despite repeated warnings from Leeds City Council, the number of Covid-19 cases in the city has risen throughout September.
In the seven days to 21 September there was a record 829 new infections identified. That surpasses the peak of new cases in the first wave of the pandemic back in late April.
Tom Riordan, chief executive of Leeds City Council, said: "What we are trying to do is give a simple message - you shouldn't really mix with other households."
Mr Riordan added: "I think we know from the experience of Leicester, Greater Manchester and West Yorkshire that when these restrictions are brought in they do not tend to be lifted after a week or two."
Leeds had been on Public Health England's watchlist as an "area of enhanced support", meaning it received greater national assistance and extra testing capacity, but had so far escaped the tighter restrictions of its neighbours.
Leeds director of public health Victoria Eaton said: "The spread of the virus is very dynamic across the city. It's clear to see we have very widespread community transmissions right across the city."
Ms Eaton said there were "high rates in some of our student areas" but said cases were rising in all age groups, not just young adults.