Born Sonia Isaacman in 1922, she joined the Communist Party in 1942 and gave up her university studies to do full-time political work. After the banning of the Communist Party of South Africa (CPSA) in 1950, she joined the staff of the Guardian newspaper and later became secretary of the Cape Town Peace Council. In 1951 she attended the World Youth Congress in Berlin as a member of a South African delegation that was lead by Ahmed Kathrada. In 1955 Sonia Bunting was one of the platform speakers at the Congress of the People in Kliptown where the Freedom Charter was adopted. In 1956 Sonia Bunting was arrested and charged with high treason. After being held in prison for two weeks she was finally acquitted from the marathon Treason Trial, along with 91 others in October 1958.
In 1959 she was banned from attending meetings and ordered to resign from 26 organisations. After the Sharpeville massacre in 1960, she was detained for three and half months at Pretoria Central Prison and in 1962 placed under house arrest with her husband Brian. In 1963 Sonia Bunting went into exile and there she continued her work for the Communist Party and held numerous positions in the liberation movement including running the only office of the CPSA in the world for twenty years.
Sonia was the organiser of the World Campaign for the Release of South African Political Prisoners, which mobilised worldwide support for the Rivonia accused and played a significant part in saving Nelson Mandela and other leaders from the death penalty. In 1991, after the unbanning of the African National Congress (ANC) and CPSA, Sonia and her husband Brian returned to Cape Town where they continued their political work. Sonia was a founder member of the Cape Town Friends of Cuba Society. She died in Cape Town in March 2001.