Ms Molewa has taught at Moloto and Makaunyane Secondary Schools from 1976 to 1981. Between 1976 and 1990 she had been involved in the underground structures of the liberation movement during that period, she had served as Chairperson of South African Commercial, Catering and Allied Workers Union (SACCAWU) at Warmbaths Branch and became a member of the Federation of Transvaal Women during the period 1984 to 1990.
She became a Deputy President of South African Commercial, Catering and Allied Workers Union (SACCAWU); a member of the Federation of Transvaal Women; a member of the Regional Executive Committee of Congress of South African Trade Union (COSATU), Northern Transvaal from 1987 to 1989 and served on the National Labour Economic Institute between 1992 and 1994.
From 1992 to 1994, Ms Molewa became a Deputy Chairperson of the African National Congress Womens League, Garankuwa Branch; and a member of the National Assembly from 1994 to 1996. She was the first women Chairperson of the Portfolio Committee on Trade and Industry during the period 1994 to 1996.
Prior to her appointment as Minister of Water and Environmental Affairs, Ms Molewa had served as Minister of Social Development from 11 May 2009 to 31 October 2010 as Premier of North West Province from April 2004 to May 2009; as a member of the Executive Council (MEC) for Tourism, Environment and Conservation in North West Province from 1996 to 1998; as MEC for Economic Development and Tourism in North West Province from 1998 to 2000; and as MEC for Agriculture, Conservation and Environment in North West Province from 2000 to 2004.
She has also served as Chairperson of the ANCWL in the North West Province; as Provincial Treasurer of the African National Congress (ANC) in the North West Province until May 2005 and as Chairperson of ANC in the North West Province from May 2005 to May 2008.