Cheryl Gillan has confirmed on Twitter that she'll be returning to the back benches, as David Cameron's reshuffle gets under way.
It came as a response to a similar announcement by Baroness Sayeeda Warsi last night, who is due to be replaced as co-chairman of the Conservative Party.
Mrs Gillan has served as Welsh Secretary since 2010, and described serving in the Cabinet as "a great privilege".
Her replacement is expected to be announced later today. Previously, Welsh Conservative MPs have urged the Prime Minister to choose an MP with a Welsh seat as her successor.