Van der Linde has been signed to provide injury cover for Tongan international, and last season's top try scorer, Halani Aulika, who is sidelined with a serious Achilles injury.
"CJ is a 70-plus cap Springbok and has been brought in to replace Halani Aulika as a starting tighthead," said London Irish director of rugby Brian Smith.
"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. I know (forwards coach) Glenn Delaney and (scrum coach) Phil Keith-Roach are keen to work with a World Cup winning tighthead.
"We are excited about what he brings to the party and he will help develop the other players we have invested in."
Van der Linde joins from the Golden Lions, whom he helped to the Currie Cup semi-finals this year, and has also played Super Rugby for the Cheetahs, Cats and Stormers.
He joined Leinster in 2008 and stayed until 2010 but missed the 2009 Heineken Cup Final win over Leicester Tigers as the Irish outfit claimed their first continental crown. The 33-year-old won the globe's greatest prize with the Springboks in 2007 and represented his country for a decade between 2002 and 2012.
His arrival comes at a time when Irish are struggling in the Aviva Premiership, with two wins in nine games leaving them just one place off the foot of the table. But they are in fine form in Europe having recorded three straight wins, including a vital victory over Stade Francais in Reading last week.
The news follows the announcement that the club has been taken over by a consortium of Irish businessmen, led by Mick Crossan, executive chairman of their primary sponsor Powerday.
The Exiles will hope that the new investment, which has led to Van der Linde's capture, will allow them to keep the likes of Marland Yarde and James O'Connor at the club next season.
"We really appreciate the investment, they are great supporters of this club and have been for some time. It is exciting times from my perspective," added Smith.
"The new owners have committed substantial new funds to the club that will be used to invest in the centre of excellence, to strengthen the playing squad, to re-invigorate the club's academy and to invest in experienced management and support staff," read a statement on the official London Irish website.