The 30-year-old loose head has now signed for Guinness Premiership outfit Saracens ahead of the 2010/11 season.
Carstens has made 80 appearances for the Sharks in Super rugby and was a part of the Sharks side beaten 39-3 by Britain and Ireland's elite in the fourth match of the 2009 tour.
His signing comes days after Sarries stated that they would not block Soane Tonga'uiha's wish to stay at Northampton despite the in-form Tongan having supposedly committed himself to a move to Vicarage Road earlier this year.
"Sometimes in life things just seem to work in your favour - we are delighted to have signed Deon for next season," Saracens' director of rugby Brendan Venter.
"More than a world class loosehead on the field, he is also an outgoing and infectious character - exactly the kind of person who will enjoy and enhance the spirit within our squad."