Mrinalini was born in Kerala on 11 May 1918, the daughter of social worker and former parliament member Ammu Swaminathan. She spent her childhood in Switzerland, where, she received her first lessons in the Dalcroze school, a Western technique of dance movements. She was educated at Shantiniketan under the guidance of Rabindranath Tagore where she realised her true calling. She then went for a short time to the United States where she enrolled in the American Academy of Dramatic Arts. On returning to India, she began her training in the south Indian classical dance form of Bharatanatyam under Meenakshi Sundaram Pillai and the classical dance-drama of Kathakali under the legendary Guru Thakazhi Kunchu Kurup.