He appointed a string of new Cabinet ministers to replace MPs who quit as part of the mass ministerial exodus in protest at his leadership.
The appointments include Greg Clark who has been made Levelling Up Secretary, a day after Mr Johnson sacked his predecessor Michael Gove.
Sir Robert Buckland has been made Secretary of State for Wales, following the departure of Simon Hart.
The former Lord Chancellor accepted the offer of a Cabinet post just hours after questioning Mr Johnson’s integrity and saying he “can no longer go on”.
James Cleverly has been appointed Education Secretary, making him the third person in that role in 48 hours, and the seventh in eight years.
Nadhim Zahawi was in the post on Tuesday afternoon before being appointed Chancellor, to be replaced by Michelle Donelan before she quit on Thursday.
Mr Cleverly, one of Mr Johnson’s oldest allies from his time as Mayor of London, stood behind the Prime Minister after June’s confidence vote, saying it had been a “clear win” for Mr Johnson.
Downing Street appointed Kit Malthouse as Chancellor for the Duchy of Lancaster, the most senior minister in the Cabinet Office after the Prime Minister.
He succeeds Steve Barclay, who was made Mr Johnson’s new Health Secretary on Tuesday.
Mr Malthouse, seen as another of Mr Johnson’s long-standing City Hall allies, was previously a minister of state in the Home Office and Ministry of Justice.
After his appointment, he tweeted Mr Johnson had made “the right decision”.
“Yesterday I was clear with the Prime Minister about my assessment of the political and ethical landscape that he faced, and the best course of action for the good governance of the country”.
He added that he hoped to “provide stability during this period” in his new role.
Shailesh Vara was appointed Secretary of State for Northern Ireland, after his predecessor Brandon Lewis resigned earlier on Thursday.
Before his appointment, he tweeted that it was “the right decision” by Mr Johnson to resign.
Andrew Stephenson was appointed Minister without Portfolio and will attend Cabinet, No 10 said.