World number four Westwood, who won the event in 2010 by eight shots and in 2011 by two, will bid to become the first man to win the tournament for a third consecutive year.
Westwood has been joined in the field by six of his victorious European Ryder Cup team mates, British duo Paul Lawrie and Justin Rose, Belgium's Nicolas Colsaerts, Sweden's Peter Hanson, German Martin Kaymer and Italy's Francesco Molinari.
Tournament director Alastair Roper said that Europe's Ryder Cup success was a good sign for the Nedbank Golf Challenge.
"It was marvellous for us that the Ryder Cup happened at the right time for us," Roper said ahead of the $5 million tournament which starts on November 29 at the Gary Player Country Club at Sun City.
"It bodes well for a good tournament because it shows that the players are at height of their game," he added.
One glaring omission from the line-up is this year's British Open champion Ernie Els.
The South African has won the Nedbank Golf Challenge on three occasions but Roper said Els, who has two children at school in America, had declined an invitation in order to spend more time with his family.
"The time of year is a bit difficult (for Els). He wants to spend time with family and has decided to miss this year. We respect his decision and we hope to see him back (in the tournament) again," said Roper.
Bill Haas, the 2011 Fedex Cup winner, is the lone American in the field, while South Africa has three representatives despite Els' decision not to play.
Louis Oosthuizen, the 2010 British Open champion, and Charl Schwartzel, the 2011 Masters champion, will be joined by 34-year-old Garth Mulroy.
Sweden's Carl Pettersson, who is based in America, rounds out the 12-man field.