Born in a Transkei village of subsistence farmers, Tambo attended Anglican and Methodist mission schools and the University of Fort Hare (B.S., 1941) and later studied law. In 1944 with Nelson Mandela (Mandela, Nelson) and others, he cofounded the Youth League of the ANC and, after teaching school briefly, began engaging wholly in nationalist politics and legal cases, rising concurrently in the ranks of the ANC. Joining with Mandela in establishing South Africa's first black law practice in 1952, he was arrested on treason charges in 1956 but was released the following year. In 1958 he became ANC deputy president. Two days after the Sharpeville Massacre, the ANC was banned (March 23, 1960), and Tambo left South Africa to help set up the organization's foreign headquarters, eventually settling in Lusaka, Zambia. He assumed the presidency of the ANC in 1969, two years after the death of its old leader, Chief Albert Luthuli.

Tambo returned to South Africa from exile on Dec. 13, 1990, to attend the first full-scale conference of ANC members (including exiles and the formerly imprisoned) in more than 30 years. However, because of ill health owing to an earlier stroke, Tambo yielded ANC executive duties to his old colleague Mandela and took the largely honorary post of national chairman of the ANC in 1991.