Immelman started his refereeing career in 2010 at the Vodacom Cup, before taking over at Varsity Cup level and later Currie Cup.
In 2016, he was added to the referees' roster for the 2016 Super Rugby season for the first time, with his Super Rugby debut match between the Sunwolves and Cheetahs in the Singapore National Stadium, the first ever Super Rugby match to be played in Singapore.
