In the British Government, the Cabinet Secretary, or more formally Secretary of the Cabinet, is the senior civil servant in charge of the Cabinet Office, a department that provides administrative support to the Prime Minister, the Cabinet, and the government as a whole.

The Cabinet Secretary is also usually the Head of the Home Civil Service, and in this role is responsible for all the civil servants of the various departments within government. This is a complicated role, as the departments and their senior civil servants (Permanent Secretaries) tend to jealously guard their independence from Downing Street.

The responsibilities of the job vary from time to time and depend very much on the personal qualities of both the Prime Minister and the Cabinet Secretary. 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. For instance, the Cabinet Secretary is responsible for administering the Ministerial Code which governs the conduct of ministers (also known as the Rule Book and formerly Questions of Procedure for Ministers). In this duty the Cabinet Secretary may be asked to investigate "leaks" within government, and enforce cabinet discipline. Unusually in a democracy, this gives the unelected Cabinet Secretary some authority over elected ministers, although the constitutional authority of the Code is somewhat ambiguous.

The Cabinet Secretary also has some responsibility for overseeing the intelligence services and their relationship to the government. In the current Blair government, this responsibility has been delegated to Security and Intelligence Co-ordinator and Permanent Secretary, Sir David Omand , while the Cabinet Secretary, Sir Andrew Turnbull has been asked to prioritize civil service reforms, including the expansion of e-government.

Secretaries of the Cabinet since 1963

The position was created in 1916 and combined with that of Head of the Home Civil Service in 1981. The holder retires at or slightly after the Civil Service retirement age of 60 and is now customarily created a life peer.

• Sir Burke Trend, later Baron Trend (1963-1973)
• Sir John Hunt , now Baron Hunt of Tanworth (1973-1979)
• Sir Robert Armstrong, now Baron Armstrong of Ilminster (1979-1988)
• Sir Robin Butler, now Baron Butler of Brockwell (1988-1998)
• Sir Richard Wilson, now Baron Wilson of Dinton (1998-2002)
• Sir Andrew Turnbull (2002-present)