Charles III is head of state of 15 Commonwealth realms and has had 20 prime ministers throughout his reign. Within the Westminster system in each realm, the King's government is headed by a prime minister. Appointment and dismissal of prime ministers are common reserve powers that can be exercised by the King or his governors-general. To date, Charles has appointed four new prime ministers, the first being Rishi Sunak as Prime Minister of the United Kingdom on 25 October 2022 and the most recent being Jeremiah Manele as Prime Minister of Solomon Islands on 2 May 2024.

This list does not cover Commonwealth nations that are not Commonwealth realms, as Charles is not head of state in these nations. Nor does it cover holders of offices of prime minister in sub-national entities such as states, dependencies, or provinces.

• Commonwealth of Nations
• Constitutional monarchy
• List of Commonwealth heads of government