Sithembiso Tony Yengeni was born in Cape Town and grew up in two Cape townships, Gugulethu and Nyanga. He completed his matric at Fort Beaufort college in Cape Town.
Yengeni was a member of the Black Consciousness Movement (BCM) under the leadership of Steve Biko before joining the banned African National Congress (ANC) in 1976. As a result of government’s determined effort to crack down on anti-apartheid movements, Yengeni voluntarily went into exile as member of Umkhonto We Sizwe. He received military training in ANC camps in various countries (Lesotho, Botswana, Zambia and Angola) in Southern Africa. From Botswana Yengeni headed for Moscow in Russia to study for a social science diploma in 1982. Chris Hani met Yengeni in Lesotho, where they became friends.
In 1984, Yengeni married Lumka Nyamza, an ANC member in Lusaka, Zambia. When he returned to South Africa in 1986, he was appointed to lead MK in Cape Town.
A year after his return, while still trying to find his feet, Yengeni was arrested by the National Party government. He was charged with terrorism and detained for four years while awaiting trial. During his detention period Yengeni was exposed to severe torture by an anti-terrorist squad policeman, Jeffrey Benzien. The state failed to prosecute Yengeni successfully until he was granted indemnity as part of the political transition process in 1991. The case, which involved 13 co-accused, dragged on for 269 days and cost the government R5 million.
Upon his release Yengeni was elected ANC secretary in the Western Cape. In his effort to drum up support for the ANC on the eve of South Africa’s first democratic election in1994, Yengeni adopted a militant leadership style, joining in the list of Winnie Madikizela-Mandela Peter Mokaba. The ANC rewarded his efforts by awarding him an influential position as chair of parliament's Joint Standing Committee for Defence. He was also elected party Chief Whip in the National Assembly.
In October 2001, Yengeni was arrested and accused of having received a generous discount on his Mercedes Benz from an arms manufacturing company, which had benefited directly from the arms deal. He was released on R10 000 bail. In 2004 Yengeni was found guilty for defrauding parliament by receiving bribes for his luxury car. Yengeni did not immediately go to jail as he had appealed against the verdict. His appeal was not successful and he served five months of a four years’ sentence at Pollsmoor Prison in Cape Town. He was released on parole on 15 January 2007.