Ten days after Boris Johnson abruptly quit Britain’s Parliament, his former colleagues delivered a stinging rebuke to the former prime minister, overwhelmingly ratifying a report that concluded he deliberately misled lawmakers about lockdown-breaking parties held in Downing Street during the coronavirus pandemic.

The vote revealed a Conservative Party still somewhat divided by Mr. Johnson’s polarizing leadership. But rather than take a clear position on the findings, by a powerful parliamentary committee, a large proportion of Conservative lawmakers abstained and just seven members of Parliament rejected the report.

That allowed it to be accepted by the House of Commons without Conservatives having to go on the record as backing or opposing Mr. Johnson, who remains popular in some quarters of the party but detested by some voters for the double standard he tolerated over pandemic restrictions.

Prime Minister Rishi Sunak, whose resignation as chancellor of the Exchequer last summer helped precipitate Mr. Johnson’s ouster from Downing Street, did not turn up for the debate, drawing criticism from the opposition Labour Party that he lacked the courage to publicly repudiate his wayward predecessor (Mr. Sunak’s office said he was otherwise engaged, citing, among other obligations, a Downing Street meeting with his Swedish counterpart, Ulf Kristersson).

Still, however tortured the deliberations, the outcome was a damning verdict for Mr. Johnson. It foreclosed — at least for the moment — any plausible return to power for a flamboyant figure whose three years in Downing Street were marked by a landslide electoral victory in 2019 but nearly ceaseless scandals after that.

After more than five hours of discussion lawmakers voted by 354 to 7 to approve the report, a crushing victory for Mr. Johnson’s critics. In all there are 650 members of the House of Commons, but many Conservative lawmakers took no part in the proceeding and avoided upsetting either party activists who remain loyal to Mr. Johnson — or voters in general, among whom he is unpopular, according to opinion polls.

In a debate marked by sorrow, anger and occasional flashes of humor, lawmakers from both sides stood up to condemn Mr. Johnson for his duplicity and to call for Parliament to endorse the report, as a way of rebuilding trust in British public life. A handful of Tories spoke in defense of Mr. Johnson, a shrunken band of loyalists for a figure who once enjoyed firm command of the House of Commons.

Mr. Johnson’s predecessor as prime minister, Theresa May, said she would vote in favor of the report because its conclusions “strike at the heart of the bond of truth between the Parliament and the public that underpins our work.”

“I also say to fellow members of my own party, that it is doubly important for us to show that we are prepared to act when one of our own, however senior, is found wanting,” Mrs. May said, a comment that some saw as an implicit criticism of Mr. Sunak’s absence from the debate.

Harriet Harman, a Labour Party lawmaker who chaired the investigation by the Privileges Committee, the House of Commons panel that produced the report, said, “Ministers must be truthful; if not, we cannot do our job,” adding: “Mr. Johnson’s dishonesty, if left unchecked, would have contaminated all our democracy.” Several lawmakers, including Labour’s Jess Phillips, pointedly referred to the former prime minister lying — a term normally not used in the chamber but permitted in this instance because of the conclusions of the report.

Mr. Johnson resigned his parliamentary seat on June 9 after seeing an early draft of the findings of the yearlong investigation. He angrily dismissed the committee as a “kangaroo court,” even though a majority of its members was drawn from his own party.

The committee proposed revoking his parliamentary pass and said that, had he not already quit, it would have recommended a 90-day suspension from Parliament.

As a practical matter, the Commons’ acceptance of the report will have a limited effect on Mr. Johnson. Losing his pass simply means he must be accompanied by another member if he wants to enter Parliament’s buildings. But symbolically, it represents a thunderous repudiation of Mr. Johnson by his former peers.

“The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is,” said Labour’s shadow leader of the House, Thangam Debbonaire, turning the words of Mr. Johnson’s political hero Winston Churchill against him.

“This isn’t just the reasonable person test, it’s the ‘Who on earth do you think you are kidding?’ test,” Ms. Debbonaire said. “And he fails both.”

Mr. Johnson’s defenders questioned how the committee could know whether his misleading statements were deliberate, said its proposed punishments were overly harsh.

Lia Nici, a Conservative lawmaker who served as a parliamentary aide to Mr. Johnson when he was prime minister, said the report did not provide persuasive evidence that Mr. Johnson had knowingly misled Parliament. She insisted that his advisers told him that none of the parties violated social distancing guidelines.

Sensing that his support was limited, however, Mr. Johnson ultimately urged sympathizers not to vote against the committee report. The former prime minister, who turned 59 on Monday, was not in Parliament either, bringing down the curtain on this phase of his career with less drama than he often generated during his stormy tenure in Downing Street.

Mr. Johnson had made little secret of his ambitions to win back his old job as prime minister, but that would be impossible without a parliamentary seat. Parliament’s endorsement of the report does not preclude Mr. Johnson from running again, but most analysts think he is unlikely to try to do so in the next general election, which is expected in the second half of next year.

Opinion polls show that he is highly unpopular among voters in general, even if he retains the backing of a significant number of Conservative Party members who were drawn to his optimistic, pro-Brexit rhetoric.

Misleading Parliament is considered a serious breach of the rules because, lawmakers argue, without accurate information from ministers they are unable to hold the government to account — one of their main functions.

In its report, the Privileges Committee said Mr. Johnson had deliberately misled lawmakers when he assured them, after the scandal around parties during lockdown emerged, that social distancing rules had always been followed in Downing Street.

Testifying before the committee earlier this year, Mr. Johnson argued that his assurances were made in good faith. But the lawmakers found he had personal knowledge of some rule breaking, had failed to investigate other allegations properly, and that he had committed multiple “contempts” of Parliament, including through his verbal attacks on the committee.

The persistent focus on the fallout from the scandal has been a political headache for Mr. Sunak. He now faces several difficult tests of his government’s popularity in elections to replace Mr. Johnson and a handful of other colleagues in the constituencies they represented.

One ally of Mr. Johnson, Nigel Adams, resigned after failing to secure a seat in the House of Lords; a second who is in the same situation, Nadine Dorries, announced that she would quit but has not done so yet.

Another Conservative lawmaker, David Warburton, stepped down after being suspended over allegations of sexual misconduct. Mr. Warburton claimed he was denied a fair hearing by a parliamentary watchdog looking into the claims against him.

To add to Mr. Sunak’s problems, the police have said they will review a newly published video, obtained by The Daily Mirror, that appeared to show a Conservative Party campaign team drinking and dancing at a Christmas party, at a time when pandemic restrictions were in force. The police had said that a previously published photo of the same event represented insufficient evidence to prosecute.

Around two dozen people were reported to be at the party, including Shaun Bailey, who campaigned unsuccessfully to become London mayor and who was nominated for elevation to the House of Lords by Mr. Johnson as part of his resignation honors list.

Mr. Bailey left before the video was taken, though one aide who received a lesser honor on the same list, Ben Mallet, does make an appearance. Opposition politicians have called for both men to be deprived of their honors.