Sai's parents divorced shortly after Sai's birth, and Sai's mother raised Sai in the household of her own father, Sir R. P. Paranjpye, who was a renowned mathematician and an educationist and who also served in 1944-47 as India's High Commissioner in Australia. Sai thus grew up in a few different cities in India, and in Canberra, Australia.
Sai took to writing early in her life,.Sai graduated from the National School of Drama (NSD), New Delhi in 1963.Sai started her career in All India Radio (AIR) in Pune, Maharashtra, India as an announcer, and soon got involved with AIR's Children's Program.
Over the years, Sai has written and directed plays in Marathi, Hindi, and English, both for adults and children. She has written and directed thus far six feature films, two children’s films, and five documentaries. She has also written many books for children, and six of her books have won national or state level awards.
Her first made-for-TV movie, The Little Tea Shop (1972), had won the Asian Broadcasting Union Award at Teheran, Iran. Later that year, she was selected to produce the Inaugural Program of Bombay (Mumbai) Doordarshan.Sai's first feature film, Sparsh (The Touch), was released in 1980, and it won five film awards, including the National Film Award. Sparsh was followed by the comedies, Chashme Buddoor and Katha.
Sai directed several documentary movies, including those on Helping Hand (London), Talking Books, Capt. Laxmi, Warna Orchestra, and Pankaj Mullick. Sai's 1993 documentary, Choodiyan, received the National Film Award for Best Film on Social Issues.