He earned his first 2 Currie Cup caps during the 2011 season and over the following 2 campaigns he rotated with the more experienced Charl McLeod for the starting role in the number 9 jersey.

[5][6] Following McLeod's departure to Grenoble at the conclusion of the 2014 Super Rugby season, Reinach was left as the undisputed first-choice scrum half for the Sharks.

[8] On 27 February 2017, it was announced that Reinach would link up with English club Northampton Saints in the Aviva Premiership from the 2017–18 season.

He was called up to the Springbok squad for the 2014 Rugby Championship due to the absence of the injured Fourie du Preez[11] and when another experienced number 9 in Ruan Pienaar went down injured during the Boks tour of Australasia, Reinach was promoted to back-up scrum-half for the remaining two home games of the competition against Australia and New Zealand.

Reinach debuted as a second-half replacement for Francois Hougaard in South Africa's 28–10 win over Australia in Cape Town on 27 September 2014 and played a big role in the Boks bonus point try scored by Jean de Villiers in the final minute.