Mr Khan thanked Londoners for “the enormous sacrifices you have made over the last seven months” and promised “our city will get through this together.”
He conceded that the Government had “done the right thing” by extending the furlough scheme, which was due to end on Sunday, but added that he would continue to lobby ministers to ensure London receives the “financial support it needs”.
Mr Khan said in a statement: “You may not agree with or like the Government’s latest restrictions. However, we must all follow them. Please continue following the restrictions and public health guidance. We must act to protect each other.
“I know it won’t be easy, but history tells us that Londoners always pull together in times of crisis. We must once again make huge collective sacrifices now in order to prevent even greater suffering later. I will continue to lobby the Government to finally sort out a fully functioning test and trace system and the financial support London needs.
“I promise you that our city will get through this together.”
His comments came as Sir Keir Starmer criticised the Prime Minister for his initial reluctance to impose the new blanket restrictions.
The Labour leader said the delay will have a “very real” human cost, while northern leaders criticised ministers for extending the furlough for the nation despite earlier refusing it for their areas during heightened restrictions.
Sir Keir welcomed that the Prime Minister had “finally taken the decision it should have taken weeks ago” and indicated Labour would support the lockdown in a Commons vote.
“Everybody is concerned about the rise in infections, the hospital admissions and tragically the number of deaths. That’s why three weeks ago, I called for circuit-break,” Sir Keir told reporters.
“The Government completely rejected that only now to announce the self-same thing.
“Alas the delay now will cost, the lockdown will be longer, it’ll be harder and there’s a human cost which will be very, very real.”
Pubs, bars, restaurants and non-essential retail will close from Thursday until at least December 2.
The public will be told to stay at home unless they have a specific reason to leave, but schools, colleges and nurseries will remain open.
Chancellor Rishi Sunak said the furlough scheme will be extended for a further month, with the Treasury covering 80 per cent of employees’ wages to prevent further unemployment.
But Greater Manchester mayor Andy Burnham reacted angrily to this, with the Government having refused to grant the subsidy for the region as they battled over Tier 3 measures.
Mr Burnham said that “when we asked you to do that for the lowest-paid people in the North, you refused”, adding: “People here will remember that.”
Liverpool region mayor Steve Rotheram added: “Now we know for sure that the Government thinks workers in the North were worth 13 per cent less than those in the South.”
Conservative backbenchers were outraged that the media learned of the new lockdown before Mr Johnson made an announcement in Parliament.
In a WhatsApp message, the Prime Minister wrote to Tory MPs to apologise to them and assure that Downing Street had not informed journalists of the measures on Friday.
“Let me assure you that the leak was not a no10 briefing and indeed we have launched an inquiry to catch the culprit,” he wrote.
With MPs expected to vote on the measures on Wednesday, Mr Johnson will have to keep backbenchers, with a significant number of them highly sceptical of restrictions, on side.
But one of those MPs, Steve Baker, appeared to have taken on board the dire warnings from scientists after a briefing with Downing Street.
“We’ve had an amazing opportunity to robustly scrutinise the arguments, the data, the forecasts of where we’re going, and what I would say to people is the Prime Minister has a got very, very difficult choices to make,” Mr Baker told Sky News.
“And I would encourage all members of the public, and all members of Parliament, to listen extremely carefully to what the Prime Minister says today and over the coming days.”