Johannes Conradie was a Queen's Counsel and started his career as an advocate in Cape Town, South Africa.
Over time he developed a keen interest in politics and became a member of parliament for Gordonia from 26 May 1938 to 31 December 1960.
In 1951 he became Speaker of Parliament of South Africa and stayed in that position for 10 years from 19 January 1951 to 30 December 1960.
Conradie, succeeded him in death when he died in Pretoria, Gauteng, South Africa on 30 September 1967.
When he died 12 August 1966 his adoptive son inherited the farm Robertson.