The monarchy of Saint Kitts and Nevis is a system of government in which a hereditary monarch is the sovereign and head of state of Saint Kitts and Nevis. The current monarch of Saint Kitts and Nevis, since 8 September 2022, is King Charles III. As sovereign, he is the personal embodiment of the Crown of Saint Kitts and Nevis. Although the person of the sovereign is equally shared with 14 other independent countries within the Commonwealth of Nations, each country's monarchy is separate and legally distinct. As a result, the current monarch is officially titled King of Saint Christopher and Nevis and, in this capacity, he and other members of the royal family undertake public and private functions domestically and abroad as representatives of Saint Kitts and Nevis. However, the King is the only member of the royal family with any constitutional role.

Saint Kitts and Nevis, officially the Federation of Saint Kitts and Nevis, is an island country consisting of the two islands of Saint Kitts and Nevis, both located in the West Indies, in the Leeward Islands chain of the Lesser Antilles. With 261 square kilometres (101 sq mi) of territory, and roughly 50,000 inhabitants, it is the smallest sovereign state in the Western Hemisphere, in both area and population, as well as the world's smallest sovereign federation. The country is a Commonwealth realm, with Charles III as King and head of state.