Cobus Reinach will leave the Northampton Saints at the end of the 2019-20 European season.
The 29-year-old scrumhalf has played 70 matches for Saints since joining the club in 2017, scoring 29 tries.
‘I love playing for Saints and living in Northamptonshire,’ Reinach said. ‘We have a fantastic group of coaches and staff, and an exciting squad that I believe can challenge for the major honours, so this has not been an easy decision for me to make.
‘Saints will always have a special place in my heart and I look forward to giving everything I’ve got to make sure we finish the season with some silverware.’
Reinach is reportedly set to join French club Montpellier.