He was a leader of the African National Congress (ANC) and of the South African Communist Party. After the Rivonia Trial, he was imprisoned for treason against the white minority South Africa government (1964 - 1987) with Nelson Mandela and Walter Sisulu. Mbeki was released from custody after serving 24 years in the Robben Island prison on November 5, 1987.
He was later vice-president of South Africa's Senate from 1994 to 1999.