Boris Johnson is stepping down immediately as a Tory MP after receiving an advance copy of the Partygate report.
The report by the MP-led Privileges Committee looked into whether he misled Parliament over lockdown-breaking parties at Downing Street.
The ex-PM angrily accused the inquiry of trying to “drive me out”.
The Privileges Committee said Mr Johnson had “impugned the integrity” of the House of Commons.
The committee said it had “followed the procedures and the mandate of the House at all times ” and would meet on Monday to publish its report promptly.
In the former prime minister’s fiery resignation statement, he said the process was “the very definition of a kangaroo court”.
Mr Johnson received a copy on Thursday and claimed it was “riddled with inaccuracies and reeks of prejudice”.
He did admit misleading parliament when he gave evidence to the Privileges Committee in a combative hearing in March, but denied doing it on purpose.
He said social distancing had not been “perfect” at gatherings in Downing Street during Covid lockdowns but insisted the guidelines – as he understood them – were followed at all times.
His lengthy statement went on to criticise the direction of the current conservative government.
In it, he said: “I did not lie, and I believe that in their hearts the committee know it.
Mr Johnson condemned the committee and claimed that its “purpose from the beginning has been to find me guilty, regardless of the facts”.
He said the “current prime minister and then occupant of the same building, Rishi Sunak” also believed they were “working lawfully together”.
