Princess Stéphanie turned her obsession with fashion into a career. She began modeling, appearing on runways and at fashion shows and even launching her own clothing lines. She began by studying design at the Fashion Design School in Paris. However, as she told the Los Angeles Times, she dropped out one year later. "You lose time studying fashion in school," she said. She was then hired as an intern at Christian Dior. When she expressed an interest in modeling, her father, Prince Rainier III was said to be furious. However, she persevered and launched a swimwear line with Alix de la Comble, a friend from Dior, called Pool Position in 1986. 

Turns out, even princesses can struggle to find a swimsuit that checks all of the boxes. So, Stéphanie created a range of suits that suited her just right. "We tried to make the suits as sexy as possible but never vulgar," she said to UPI at the time.

As the Los Angeles Times reported, Stéphanie initially modeled the swimsuits herself and made up to $10,000 a day. Throughout the '80s, she even appeared in magazines like Vanity Fair and Vogue. However, it wasn't long before Stéphanie decided she was done with that line of work. "I got sick of modeling and I was afraid of getting overexposed," she said.