He represented the Free State (U18: 2009 & 2010 – he was included in an SA U18 High-Performance Squad, which played matches against France, England and Namibia).
Jordaan joined the Free State Academy and appeared for the Free State U19 side (2011 & 2012) and the U21’s (2013).
Niell played for UFS Shimlas (2013-2015), started in all nine of the UFS Shimlas' matches during the 2015 Varsity Cup competition and in the final, he scored a try against the NWU Pukke as Shimlas win their first-ever Varsity Cup title.
He was included in the Free State XV (2013) and he made his first-class debut against the Sharks XV in Durban. However, he made his first appearance in the Currie Cup for the Griffons (2014).
After the 2015 Varsity Cup, Jordaan was named as the starting number eight for his Super Rugby match against the Waratahs in Bloemfontein.
Jordaan played all 10 games in the 2016 Currie Cup, including the Semi-Final against the Lions in Bloemfontein and in the Home Final against the Blue Bulls. (2016 Currie Cup Champions)
Jordaan Captained his first game for the Toyota FS Cheetahs 12 Aug 2017 against the Griquas (Currie Cup)
PRO14 debut – 1 September 2017 vs Ulster in Northern Ireland
Captain of the SuperSport Rugby Challenge in 2018, the Toyota FS XV made is to the Semi Final but lost against Griquas in Kimberley.