Fortuin started playing for local side SWD Eagles, playing for them at youth level from 1998 until he made his senior debut in 2000. He played for them for six seasons, before joining the Free State Cheetahs in 2005, where he spent a further four seasons. During this time, he also represented Super Rugby side the Cheetahs, making 22 appearances for them between 2006 and 2008.
He returned to the SWD Eagles for the 2009 Currie Cup First Division, as well as the 2010 season. In early 2011, he announced that he would be a candidate for the Democratic Alliance in the South African municipal election, 2011.[3] The SWD Rugby Union distanced themselves from him and he was not offered a contract for 2012.
During his career, he made two appearances for South Africa in international rugby.[4]
He made his debut for South Africa against Ireland in 2006. In 2007, he was included in the South African team for the 2007 Tri Nations tournament, where he played in one match against Australia.
Fortuin joined club side Blanco instead for 2011, first as a player, but later as their coach, guiding them to the 2012 National Club Championships.[5] He joined the SWD Eagles coaching staff for the 2012 season and was appointed head coach after the 2013 Vodacom Cup season.[6]
He remained the head coach for the SWD Eagles until the end of the 2015 season; he then moved to Pretoria to join the coaching staff of the Blue Bulls.[7]