The Dominion of Ceylon changed its name to Sri Lanka, adopted a new constitution, and officially became a republic within the Commonwealth.

Ceylon was an independent country in the Commonwealth of Nations from 1948 to 1972, that shared a monarch with other dominions of the Commonwealth. In 1948, the British Colony of Ceylon was granted independence as Ceylon. In 1972, the country became a republic within the Commonwealth, and its name was changed to Sri Lanka.

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian peninsula by the Gulf of Mannar and the Palk Strait. It shares a maritime border with the Maldives in the southwest, India in the northwest, Andaman and The Nicobar Islands in the northwest, and Myanmar through the Bay of Bengal. Sri Jayawardenepura Kotte is the legislative capital of Sri Lanka, while the largest city, Colombo, is the administrative and judicial capital which is the nation's political, financial and cultural centre. Kandy is the second-largest urban area and also the capital of the last native kingdom of Sri Lanka. The most spoken language Sinhala, is spoken by the majority of the population. Tamil is also spoken by approximately five million people, making it the second most-spoken language in Sri Lanka.

The republics in the Commonwealth of Nations are the sovereign states in the organisation with a republican form of government. As of June 2022, 36 out of the 56 member states were republics. While King Charles III is the titular Head of the Commonwealth, he is not the head of state of the republican members. The King is however, the reigning monarch in the Commonwealth realms. The Head of the Commonwealth role does not carry with it any power; instead, it is a symbol of the free association of Commonwealth members.