Franco van der Merwe will join Ulster at the end of the Vodacom Super Rugby season.
The 31-year-old will replace former Bok lock Johann Muller, who is retiring at the end of the European season, at the Irish club.
Van der Merwe won the Currie Cup with the Golden Lions in 2011 and earned Bok selection in 2013.
While Van der Merwe will not travel with the Lions on their Super Rugby tour to Australasia, as a result of injury, he will look to end his Lions tenure on a high as he aims to make a comeback in July.
Photo: Steve Haag/Gallo Images