Gwede Mantashe was born in the village of Lower Cala in the Transkei (now Eastern Cape). He received a B.Comm degree from the University of South Africa (Unisa) in 1997 and completed his B.Comm Honours degree in 2002.
Mantashe worked at Matla Coal where joined the trade union movement. He became the Witbank branch chairperson of the National Union of Mineworkers (NUM) in 1982, a position he held until 1984. He was then elected NUM Regional Secretary in 1985. After this Mantashe was further elevated when he was elected as National Organizer for the same union in 1988.
From 1994 Mantashe served as the Assistant Secretary-General of NUM until March 1998 when he was elected as the General Secretary. Mantashe was elected as a local government councilor in 1995 and served until 1999. In 1995 Mantahse became the first trade unionist to be appointed to the Board of Directors of a Johannesburg Stock Exchange (JSE) listed company, Samancor, a position he still holds today. In May 2006, at the 12th National Conference, he stepped down as General Secretary of NUM and was succeeded by Frans Balani. In the same year he was appointed as the Executive Director of Development Bank of Southern Africa (DBSA) and served for two years at Chairperson of the Technical Working Group of the Joint Initiative for Priority Skills Acquisition (JIPSA).
In 2007 Mantashe was elected as Chairperson of the South African Communist Party (SACP) and also served as a member of the Party’s Central Committee. At the 52nd ANC National Conference held in December 2007, Mantashe was elected as the Secretary General of the ANC. He currently serves on these two positions.
In his capacity as Secretary General of the ANC, he serves as a Central Executive Committee member of the Congress of the South African Trade Unions (COSATU) and also the International Labour Federation.
On 30 October 2011 Mantashe was admitted to Botshelong Hospital for a post surgery check up but later transferred to Sunward Park Private Hospital in (Boksburg) for treatment. He was later discharged.