She gave up her acting career at the peak after her marriage in 1989 to move to America.Sumathi is married and settled in America with their daughter and son.
Sumathi was born in Madurai; a city in Tamil Nadu, India. Her father and mother were originally from Madurai.
Her father managed several businesses such as photo studio and printing press.
Her mother, was a housewife taking care of Sumathi and her seven brothers and three sisters.
Her elder brother Master Prabhakar was the first one in the family to enter the film industry.
In 1966, Sumathi moved in with her Aunt along with Prabhakar to pursue his dreams.
Sumathi entered the film industry when a director was looking for a young baby to play a role in a Malayalam film along with veteran actor Bharath Gopi.She started her film career in Tamil movies as a child actress (Baby Sumathi) by playing the role of daughter of Gopi in the late 60's. She played dual roles and in some movies acted as a boy.Soon she moved to Telugu and Malayalam films, where she starred in many films.As Baby Sumathi grew up, she took to modeling and started endorsing many products.She has won many Nandi and Filmfare awards as a child.She acted many films with her third elder brother Master Prabhakar and second younger brother Kumar.