The 43-year-old, who has worked his way up through the junior coaching ranks at the franchise and is already coach of the Blue Bulls in the domestic Currie Cup competition, has signed a four-year contract with the Bulls.
He replaces Frans Ludeke, who stepped down in June after a disappointing season for the Pretoria-based outfit.
"This is a dream come true, the most special and memorable moment of my career thus far, it has always been my biggest dream to be head coach of the Bulls," Marais said in a statement.
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(Reporting by Mark Gleeson in Cape Town; Editing by Amlan Chakraborty)
