The 24-year-old has put pen to paper on a two-year deal at Scotstoun and will join up with Gregor Townsend's squad for pre-season training at the end of the month.
The 6ft 1in tight-head began his senior career in Pretoria, making his debut for the Blue Bulls in 2009. He went on to appear 41 times for the club, 14 of which were in Super Rugby. In 2013, De Klerk joined the Cheetahs and has made 14 appearances in the Vodacom Cup and Currie Cup, playing seven times in Super Rugby this season.
De Klerk becomes Glasgow's third prop to join the club this summer and fifth signing ahead of the 2014/15 season, following the arrivals of Alex Allan, Euan Murray, James Downey and Murray McConnell.
"I'm delighted to have signed for the Warriors and I'm looking forward to playing in the Guinness PRO12 and European Rugby Champions Cup next season," he said. "It's always been an ambition of mine to play for a European club and I'm looking forward to going over to Scotland later this month and meeting my new team-mates.
"I'm expecting tough competition to get into the team but that is a great challenge and something which really motivates me.
"Glasgow have made excellent progress over the last couple of seasons and I'm looking forward to being a part of that."
The Glasgow Warriors head coach, Gregor Townsend, said: "He'll add depth and competition to our front row. Rossouw is also very good in the loose and a strong tackler and has already played more than 20 games in Super Rugby."