The post is appointed by the prime minister with the advice of the out-going cabinet secretary and the First Civil Service Commissioner.

In most cases the true influence of the cabinet secretary extends far beyond administrative matters, and reaches to the very heart of the decision-making process.

The cabinet secretary is responsible for overseeing the intelligence services and their relationship to the government, though since 2002 this responsibility has been delegated to a full-time role (initially as Security and Intelligence Co-ordinator, now the National Security Adviser), with the cabinet secretary focussing on civil service reforms to help deliver the government's policy programme.

[5] The 2024 appointment process consisted of shortlisted candidates took "leadership assessments" and an interview chaired by the First Civil Service Commissioner Gisela Stuart, Brian McBride (Lead Non Executive Director MoD, and Non-Executive member of the Civil Service Senior Leadership Committee), Gus O’Donnell (former Cabinet Secretary) and Dame Sharon White (former Second Permanent Secretary at HM Treasury).

As of January 2025[update], Sir Chris Wormald is Cabinet Secretary and Head of the Home Civil Service and Cat Little is Cabinet Office Permanent Secretary and COO of the Civil Service; as such, the 2011 restructuring has been partially undone and two of O'Donnell's roles are again held by the same person, while the third has remained separate.