His Majesty's principal secretaries of state, or secretaries of state, are senior ministers of the Crown in the Government of the United Kingdom. Secretaries of state head most major government departments and make up the majority of the Cabinet of the United Kingdom.

The Cabinet of the United Kingdom is the senior decision-making body of His Majesty's Government. A committee of the Privy Council, it is chaired by the Prime Minister and its members include Secretaries of State and other senior ministers. Members of the Cabinet are appointed by the Prime Minister and are by convention chosen from members of the two houses of the Parliament of the United Kingdom, the House of Commons and the House of Lords.