Born as the third child to the Gilbert and Seelwathie Fonseka at Peliyagoda, Kelaniya. After Malini was born, her family moved to Jambugasmulle, Nugegoda. In 1952 she started her education at St. Johns College Nugegoda until the 5th grade. After moving the family to Wedamulle, Kelaniya she was enrolled at Gurukula Maha Vidyalaya, Kelaniya until completing her education.