Justice Secretary Michael Gove, Education Secretary Nicky Morgan and Culture Secretary John Whittingdale have all been sacked by the Prime Minister.
Key Cameron ally Oliver Letwin, Chancellor of the Ducy of Lancaster, was also expected to lose his job.
Revealing her dismissal on Twitter, Mrs Morgan wrote: “Disappointed not to be continuing as Education Secretary & Min for Women & Equalities – two wonderful roles it’s been a privilege to hold.”
Mrs Morgan had backed Mr Gove for the Tory leadership.
Mr Whittingdale posted: “Has been a privilege to serve as Culture Secretary. I wish my successor every success & will continue to support creative industries.”