Jeremy Hunt has been sacked as foreign secretary. Mr Hunt said he had been offered another role with Mr Johnson's Cabinet but has decided that he would instead return to the backbenches.
Ealier, secretary of state for Northern Ireland Karen Bradley said she had left the government on Wednesday evening, amid a wave of sackings and resignations as Boris Johnson became prime minister.
Ms Bradley said: “It has been an enormous privilege to serve as Secretary of State for Northern Ireland and represent this special nation and integral part of our precious union. I am extremely proud of our achievements over the past 18 months.”
Other senior figures to leave government on Wednesday included:
Mel Stride (Lord president and leader of the House of Commons)
Mr Stride's career in the Commons lasted jus two months. The Remain voter replaced Andrea Leadsom after Ms Leadsom quit following Theresa May's suggestion of including a second referendum in the EU withdrawal agreement.
David Mundell (Scottish secretary)
David Mundell has been sacked. Mr Mundell served in the role for nine years. He tweeted: "Disappointed but not surprised to be leaving the Scotland Office after 9 years. Will, of course, support the new Government, but as I said to PM this afternoon I will also hold him to account on his commitments to the Union. Hope there's still room on the backbenches".
James Brokenshire (Housing secretary)
MP for Old Bexley & Sidcup James Brokenshire is also out. He had served as housing secretary under Theresa May. "Has been a huge privilege to serve, but looking forward to being released from collective responsibility and campaigning on issues that matter to me and my constituents," he said on Twitter.
Damian Hinds (Education secretary)
Damian Hinds quit as education secretary saying he looks "forward to supporting the government from the backbenches".
Chris Grayling (Transport secretary)
Sky News have reported that transport secretary Chris Grayling has left the Cabinet at his own request.
Greg Clark (Business secretary)
Secretary of state for business, energy and industrial strategy Greg Clark tweeted on Wednesday: "I warmly congratulate Boris Johnson on becoming Prime Minister. He is right to appoint a new team for a new premiership and I wish him and them well for the vital work ahead.
“It has been an honour to serve the country as Secretary of State for Business, Energy and Industrial Strategy for the last 3 years; and as Communities Secretary, Universities & Science Minister, Cities Minister, Financial Secretary to the Treasury & Planning Minister.”
Liam Fox (Secretary of state for international trade)
The seventh resignation on Wednesday came from Liam Fox, who had served as the UK's secretary of state for international trade for three years.
“The world-class trade department we have built leaves the UK uniquely well-positioned to forge our new trading relationships beyond Europe and create a truly Global Britain,” he said in a thread of tweets.” But we must first undertake the momentous task of delivering on the instruction of the British people and leave the European Union. I look forward to supporting @BorisJohnson and the government from the backbenches.”
Penny Mordaunt (Defence secretary)
Ms Mordaunt announced that she would be leaving government on Wednesday afternoon, shortly after Boris Johnson completed his first speech as prime minister outside Downing Street.
She tweeted: “I’m heading to the backbenches from where the PM will have my full support, as will my successors at @DefenceHQ & @WomenEqualities. Thank you to everyone who’s helped me get things done, especially our Armed Forces and civilians in defence for the last 85 days. We achieved much”.
David Lidington (Cabinet office minister, Theresa May's de facto deputy)
Announced resignation on Twitter. "I wrote to @BorisJohnson yesterday to congratulate him on his election, to wish him well & to say I've decided that after 20 yrs on the front bench it's the right moment to move on. I shall leave the govt when @theresa_may offers her resignation to The Queen."
Philip Hammond (chancellor of the exchequer)
Hammond, a staunch opponent of a no-deal Brexit, said the new prime minister should be "free to choose a chancellor who is fully aligned with his policy position".
In his resignation statement, he said: “We bequeath to our successors genuine choices, once a Brexit deal is done: the ability to choose, within the fiscal rules, between increased public spending, reduced taxes, higher investment or progress towards faster debt reduction – or some combination of all four. After a decade when the aftermath of the 2008-09 recession meant we had no choices, this is a luxury which our successors should use wisely.”
Rory Stewart ( International development secretary)
Confirming his resignation on Twitter, former leadership candidate Rory Stewart posted an image of Sky News reporting his departure with an upside down smiley emoji.
David Gauke (Justice secretary)
"Given Boris's stated policy of leaving the EU by 31 October at all costs, I am not willing to serve in his Government," he wrote in his resignation statement. "I believe I can most effectively make the case against a no deal Brexit from the backbenches."
Mick Davis (Conservatives chief executive and treasurer)
In his resignation statement, Davis warned that the party risks a "very bad outcome" of putting Jeremy Corbyn in government if it is not properly resourced. The mining tycoon who has been the party's most generous donor over the last six years wrote to the party's benefactors on Wednesday saying "one of my greatest bugbears has been the lack of unity in our party".
Anne Milton (Education minister)
"I have grave concerns about leaving the EU without a deal . . . Having abstained in the vote last week, today I have resigned from the Government. It has been an honour to serve on the Conservative frontbenches, my thanks to everyone I have had the pleasure of working alongside."
Alan Duncan (Foreign office minister)
Mr Duncan resigned as a foreign office minister on Monday to seek a Commons vote that could have prevented Boris Johnson from becoming prime minister. Duncan said he could not serve under Johnson, whom he has previously described as a "circus act", and asked speaker John Bercow to test whether the former foreign secretary would command the confidence of the house as prime minister. The speaker rejected his call.