Elected member of the brief 11th Congress of Deputies in the December 2015 general election in representation of Toledo, she chaired the newly created Joint Congress-Senate Committee on National Security from 24 February 2016 to 3 May 2016. She renovated her seat at the June 2016 general election, and, on 3 November 2016, Cospedal was appointed Minister of Defense by PM Mariano Rajoy, an office she held until June 2018, when a vote of no-confidence ousted the government.