The designer will be a consultant on the live finals of the series, and will "help guide the finalists' style transformations as they fight for their chance to become the next American Idol.
"I am honoured to be joining the 11th season of American Idol," femalefirst.co.uk quoted the 60-year-old as saying.
"My own experiences at the beginning of my career inspired my commitment to mentor young people who are dedicated to pursing their dreams. I look forward to working with the artists to guide them in defining their performance style and identity," he added.
The final is scheduled for March beginning on Friday.