Johann began his career as a secondary school teacher. After further post-graduate studies he lectured at tertiary level in Educational Psychology and Sociology. Whilst studying law part-time, Johann completed his articles at Macintosh Cross and Farquharson in Pretoria, whereafter he moved to Cape Town and was appointed as a Professional Assistant at Walkers. After three years he founded and remained a partner at Jacobs and Pieterse for six years, then returned to Walkers as a Director for a period of six years. After a short period in New Zealand as a senior advisor at a large trust company, he returned to South Africa in August 2008 to take up an appointment as a Director and the National Practice Head at Cliffe Dekker (now Cliffe Dekker Hofmeyr). Johann retired from directorship at Cliffe Dekker Hofmeyr with effect from 31 March 2019, when he took up the position of Consultant.
Johann was appointed as an examiner for the Attorneys Admission examination in August 2011, and was appointed as a member of the FISA Disciplinary Committee in 2013. He became Chairman of the Disciplinary Committee in 2014 and remained in office until his retirement from the Disciplinary Committee at the end of March 2019.