Mzu Mthombeni practises as an advocate. He has acted in the Labour Court on several occasions. He has considerable experience of training in mediation, arbitration and conflict management. Prior to joining the Bar, Mzu worked as an attorney in private practice and was a senior partner in Mthombeni and Associates Attorneys.

He was admitted as an attorney in 1989. He was a senior researcher at Unisa from 1988 to 1989 and from 1990 to 1996 lectured extensively as an Associate Professor in Commercial and Labour Law at Vista University, Soweto. After his academic career, he worked at the CCMA where he was Convening Senior Commissioner in KwaZulu-Natal in 1998, Senior Commissioner in Gauteng in 1997 and in 1999 National Senior Commissioner at its head office. He was a part-time Senior Commissioner at the CCMA from 2000 until 2003. An International Labour Organisation accredited trainer, Mzu was involved in training the first CCMA commissioners in 1996. From 1993 to 1999 he was an IMSSA accredited mediator, facilitator, trainer and arbitrator. From 2000 to 2001, he was a panellist and later the Chairperson of the Public Health and Welfare Sectoral Bargaining Council (PWSBC).

Since 2000 he has been a panellist on the Education Labour Relations Council (ELRC) and the Safety and Security Sectoral Bargaining Council (SSSBC). He is also on the panel of the National Bargaining Council for the Chemical Industry (NBCCI) (from 2001), South African Local Bargaining Council (SALGA) (from 2003), and the Metal and Engineering Industries Bargaining Council (MEIBC). He was also the Chairperson of SSSBC from June 2002 to May 2008. He was a member of the Advisory Appeals Committee for the Gauteng Department of Health from 2001 until 2008.