Kankowski was first selected to represent South Africa during the Springboks 2007 end of year tour to Wales and England.

He made a try-scoring test debut on the tour as a substitute during South Africa's 34–12 victory over Wales at the Millennium Stadium on 24 November 2007.

His most productive year was in 2008, receiving award nominations for his performances at Super Rugby and provincial level and was subsequently rewarded by being part of the Springboks Incoming Tour, their Tri Nations squad and their end of year Outgoing Tour.

He was also part of the Springbok squad selected to play three tests against the British & Irish Lions on their tour of South Africa in 2009.

[2] In June 2017, it was announced that Kankowski would join the Golden Lions for the 2017 Currie Cup season.