The South Africa international has arrived at the club after a group of Irish businessmen led by Mick Crossan, who is the executive chairman of Irish's principal sponsor Powerday, completed a takeover.
Director of rugby Brian Smith told the club's official website: "CJ is a 70-plus cap Springbok and has been brought in to replace Halani Aulika as a starting tighthead. He's a world class scrummager and will bring a lot of experience and composure to our pack, particularly at scrum time.
"His arrival is timely as we look to re-establish ourselves as a dominant scrum in the Premiership. I know Glenn Delaney and Phil Keith-Roach are keen to work with a World Cup-winning tighthead."
Van der Linde has 75 Springboks caps to his name.