The Cabinet Office is a ministerial department of the Government of the United Kingdom. It is responsible for supporting the prime minister and Cabinet. It is composed of various units that support Cabinet committees and coordinate the delivery of government objectives via other departments. As of December 2021, it had over 10,200 staff, mostly civil servants, some of whom work in Whitehall. Staff working in the Prime Minister's Office are part of the Cabinet Office.

The prime minister of the United Kingdom is the head of government of the United Kingdom. The prime minister advises the sovereign on the exercise of much of the royal prerogative, chairs the Cabinet and selects its ministers. As modern prime ministers hold office by virtue of their ability to command the confidence of the House of Commons, they sit as members of Parliament. The current prime minister is Rishi Sunak of the Conservative Party, who assumed the office on 25 October 2022.