He played for the Free State Cheetahs in 2003, before moving to Durban in 2005 to spend the bulk of his career at the Sharks. A native of the town of Bethlehem in the Free State province, Bismarck du Plessis made his debut for the Sharks in Super Rugby (then the Super 12) in 2005. As he plays hooker and played in the same team as South Africa"s past captain, John Smit, for much of his career he had been a backup to Smit.
However, this changed when Smit moved to tighthead property
The Du Plessis brothers became the 23rd set of brothers to earn caps for South Africa at rugby union. During the 2008 end-of-year Test series, the Springboks moved Smit to tighthead in order to accommodate both him and the younger, faster Du Plessis in the front row together.
This change has continued through the 2009 Super 14 season and into the Boks" 2009 Test season. After South Africa"s second game of the 2008 Tri Nations Series, against New Zealand, Du Plessis was cited for an eye-gouge on New Zealand"s Adam Thomson.
At the subsequent disciplinary hearing, which was the first of his career, the judicial officer found that his action had been "careless", not deliberate, and imposed a three-week suspension, a significantly lower penalty than the three-to-six months" suspensions routinely imposed for deliberate eye-gouging.
During the Rugby Championship, Du Plessis received two yellow cards in a match against New Zealand and was then issued a red card. The Institutional Review Board later admitted an error in one of the yellow cards. This red card was later overturned by the Institutional Review Board and struck from Du Plessis" record.