MGR was a member of the Congress Party till 1953 and he used to wear kathar and wear vibhuti on his forehead. In 1953 MGR joined the DMK. He became a vocal Tamil and Dravidian nationalist and prominent member of the DMK (Dravidian Progressive Federation). He added glamour to the Dravidian movement which was sweeping Tamil Nadu. He became a member of the state Legislative Council in 1962. He was first elected to the Tamil Nadu Legislative Assembly in 1967. After the death of his mentor, Annadurai, MGR became the treasurer of DMK in 1969 after Karunanidhi became the chief minister.

In 1967, he was shot in the neck by fellow actor and political aspirant M.R. Radha. The bullet was permanently lodged in his neck and his voice damaged. He wanted the financial details of the party to be publicised which enraged the leadership of DMK and in 1972, MGR was expelled from the party. MGR then floated a new party named Anna Dravida Munnetra Kazhagam (ADMK) which was later renamed All India Anna Dravida Munnetra Kazhagam (AIADMK), the only powerful opponent of the DMK. He became Chief Minister of Tamil Nadu in 1977, and remained in office till his death in 1987. In 1979, Members of his party became the first dravidian and non-congress party from Tamil Nadu to become ministers in the Union Cabinet. It is to be noted that the AIADMK won every state assembly election as long as MGR was alive. He was the first film actor to be a Chief Minister in India.