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.

In the executive branch, the head of government is the highest or the second-highest official of a sovereign state, a federated state, or a self-governing colony, autonomous region, or other government who often presides over a cabinet, a group of ministers or secretaries who lead executive departments.