Roberts, 26, is working with stylist Lysa Cooper and designer Henry Holland on the show, which sees hopefuls compete to create an outfit for the 'Where Have You Been' hitmaker to wear, reported Femalefirst.
"I was really excited to be working with Rihanna to find a new British up-and-coming designer. I was so flattered when she asked me. She is definitely one of my style icons," she said.
Roberts also said the panel were eager to find an exciting designer who would "think outside the box" but had to remind themselves that the contestants were new to the celebrity world.
"We were looking for someone who could think outside the box and who wouldn't give up at the first hurdle.
"I appreciated the fact that these young designers had been taken out of real life and were in a bubble where they were designing outfits for some of the world's biggest pop stars."