Sumithra was born to Ragavan Nair and Janaki. Her father was working in an oil refining company and has three brothers. When she was doing her schooling she learnt dance from Murugappan Master. She started her career at her 19 years in the movie Nrithasala in 1974, directed by A.P Raj. She made her debut in Nirmalayam. She has acted in over 200 films in Malayalam, Tamil, Telugu, and Kannada languages. In Tamil, Avalum Penn Thaane (1974) was her first movie. Later in 1975 she made her debut Kannada movie Mugiyada Kathe. Sumithra acted as heroine with Rajini and Kamal as well as she acted as mother to both of them. She has acted with leading heroes like Vishnuvardhan, Rajesh in Kannada, Sivaji Ganesan, Jaishankar, Sivakumar, Rajinikanth and Kamal Haasan in Tamil. She's performed supporting roles in hundreds of Kannada, Tamil, Malayalam,and Telugu movies. She is married to notable Kannada film director D. Rajendra Babu and has two daughters.