Boris Johnson says he accepts Sue Gray's findings in full in her investigation into parties in Downing Street in lockdown.
He said he apologises, and says now is a time we must 'learn'.
He said immediate changes will be made to the way Downing Street and the Cabinet Office will run.
Prime Minister Boris Johnson told the Commons: “Firstly, I want to say sorry – and I’m sorry for the things we simply didn’t get right and also sorry for the way this matter has been handled.
“It’s no use saying this or that was within the rules and it’s no use saying people were working hard. This pandemic was hard for everyone.”
He says they will address the fragmented and complicated leadership structures in Downing Street - including creating an 'Office of the Prime Minister'.
He says he will make sure that codes of conduct for civil servants will be enforced, and he says there will be announcements of more improvements in the days ahead.
Mr Johnson said that “we are making changes now to the way Downing Street and the Cabinet Office run so that we can get on with the job that I was elected to do and the job that this Government was elected to do”.
He added: “First it is time to sort out what Sue Gray rightly calls the fragmented and complicated leadership structures of Downing Street which she says have not evolved sufficiently to meet the demands of the expansion of Number 10 and we will do that, including by creating an Office of the Prime Minister with a permanent secretary to lead Number 10.”
He said: "I get it and I will fix it. And I want to say to the people of this country 'I know what the issue is', it's whether this country can be trusted to deliver and I say yes we can be trusted."
Labour leader Sir Keir Starmer said 12 parties have reach the threshold for criminal investigation by police.
Boris Johnson faced shouts of “resign” from Opposition MPs as he told the Commons: “We asked people across this country to make the most extraordinary sacrifices – not to meet loved ones, not to visit relatives before they died, and I understand the anger that people feel.
“But it isn’t enough to say sorry. This is a moment when we must look at ourselves in the mirror and we must learn.
“While the Metropolitan Police must yet complete their investigation, and that means there are no details of specific events in Sue Gray’s report, I of course accept Sue Gray’s general findings in full, and above all her recommendation that we must learn from these events and act now.”
Labour deputy leader Angela Rayner told Sky News: “I think that would be terrible for the Conservative Party and MPs to try and blame civil servants when it is the Prime Minister himself that has to take responsibility here.”
She said Tory MPs should not try to “prop up the Prime Minister when they know he’s broke the law, when they know he’s acted inappropriately”.
She added: “If they choose to try and defend that, then I think what actually will happen is it will have a devastating impact on the brand of Conservatives who have always prided themselves on upholding the British principles, upholding the law of the country, and I think it will start to erode the trust and frustrate Conservative voters.”
Concluding his statement on the Sue Gray report, Boris Johnson said: “I get it, and I will fix it. I want to say to the people of this country I know what the issue is.”
Labour MPs should back: “You!”
The Prime Minister continued: “It is whether this Government can be trusted to deliver, and I say ‘yes we can be trusted to deliver’.”
He added: “The reason we are coming out of Covid so fast is at least partly because we doubled the speed of the booster rollout and I can tell the House and this country that we are going to bring the same energy and commitment to getting on with the job to delivering for the British people and to our mission to unite and level up across this country.”
Sir Keir Starmer told MPs: “By routinely breaking the rules he set, the Prime Minister took us all for fools, he held people’s sacrifice in contempt, he showed himself unfit for office.
“His desperate denials since he was exposed have only made matters worse. Rather than come clean, every step of the way he’s insulted the public’s intelligence.
“And now he’s finally fallen back on his usual excuse: it’s everybody’s fault but his. They go, he stays. Even now he is hiding behind a police investigation into criminality in his home and his office.
“He gleefully treats what should be a mark of shame as a welcome shield. But Prime Minister, the British public aren’t fools, they never believed a word of it, they think the Prime Minister should do the decent thing and resign.
“Of course he won’t because he is a man without shame and just as he has done throughout his life, he’s damaged everyone and everything around him along the way.
“His colleagues have spent weeks defending the indefensible, touring the TV studios parroting his absurd denials, degrading themselves and their offices, fraying the bond of trust between the Government and the public, eroding our democracy and the rule of law.”
