A report by senior civil servant Sue Gray into lockdown-breaking gatherings at Downing Street under Johnson condemned some of the behavior in government as being "difficult to justify".
"I want to say sorry," Johnson told parliament. "Sorry for the things we simply did not get right and sorry for the way that this matter has been handled."
Johnson said the government had to learn from the criticisms raised, and that he would make changes to his Downing Street operation.
"I get it and I will fix it," he said. "And I want to say to the people of this country. I know what the issue is, it is whether this government can be trusted to deliver and I say yes we can be trusted, yes we can be trusted to deliver."
Gray's report looked into what has become weeks of a steady drip of stories about events in Downing Street during the COVID-19 lockdown, with reports of aides stuffing a suitcase full of supermarket alcohol and dancing until the early hours.
However, parts of the report were not published due to the ongoing police investigation, which could take months.
Johnson, facing the greatest threat to his premiership yet, has so far weathered calls from opponents and some in his own party to resign by saying people needed to wait for the report.
