Work and Pensions minister Penny Mordaunt has been appointed as Witham MP Priti Patel's replacement in the cabinet.
Ms Patel resigned as International Development Secretary on Wednesday after it emerged she attended a series of unauthorised meetings with Israeli officials.
Like Ms Patel, Portsmouth North MP Ms Mordaunt backed Leave in the EU referendum.
Read: Who is Penny Mordaunt?
The announcement marks the second reshuffle in a week for Theresa May.