Karan, Dibakar Banerjee, Zoya Akhtar and Anurag Kashyap have directed four different short films for "Bombay Talkies", a tribute to 100 years of Indian cinema.
"Karan will call his fashion designer friends and discuss Dibakar, Anurag and Zoya's looks for their red-carpet appearances with them," said a source.
The Cannes fest starts May 15 and "Bombay Talkies" will be screened May 19.
Karan, known for his fashion and style sense, is excited about his Cannes stint.
"I'm extremely honoured that our endeavour has been officially selected at Cannes. I can't wait to walk the red carpet with Dibakar, Anurag and Zoya. I'd love to get them dressed for Cannes," he said.
"Bombay Talkies" will release in India on May 3.