The Tamil Nadu government is the administrative body responsible for the governance of the state of Tamil Nadu, functioning as a state-level parliamentary institution within the federal structure of India. Its constitutional framework is determined by the Constitution of India of 1950. The state originated from the Madras Presidency of British India, which became Madras State upon the adoption of the Constitution on January 26, 1950. The state was linguistically reorganized in 1956 under the States Reorganisation Act. The name was officially changed from Madras State to Tamil Nadu ("Tamil Country") on January 14, 1969, under Chief Minister C.N. Annadurai, to reflect the linguistic and cultural identity of the region.
The government operates on a parliamentary model with three branches: the executive, the legislature, and the judiciary. The Governor, appointed by the President of India, is the de jure constitutional head of the state. The de facto executive power rests with the Chief Minister and the Council of Ministers, who are collectively responsible to the legislature. The lawmaking body is the Tamil Nadu Legislative Assembly (Vidhan Sabha), which has 234 directly elected members (MLAs). The state's judicial system is headed by the Madras High Court.
A significant structural change occurred in 1986 when the legislature transitioned from a bicameral to a unicameral system, abolishing the Tamil Nadu Legislative Council. The political landscape is historically connected to the dominance of Dravidian parties, primarily the Dravida Munnetra Kazhagam (DMK) and the All India Anna Dravida Munnetra Kazhagam (AIADMK).