“As part of his role as chief creative officer, Mr Simons will oversee all aspects of design, global marketing and communications, and visual creative services,” the company announced on Facebook.
Simons, 48, quit as creative director at Christian Dior last October after more than three years at the helm of the French giant.
He had taken over in April 2012 after British designer John Galliano was fired following an outcry over anti-Semitic insults he made in a Paris bar that were caught on camera.
“Not since Mr Klein himself was at the company has it been led by one creative visionary, and I am confident that this decision will drive the Calvin Klein brand and have a significant impact,” said Calvin Klein CEO Steve Shiffman.
“Raf’s exceptional contributions have shaped and modernised fashion as we see it today and, under his direction, Calvin Klein will further solidify its position as a leading global lifestyle brand,” he added.