The Italian designer dreams of dressing the British royal and thinks she would look great in one of his more daring and glamorous gowns rather than the ladylike look she usually favours.
He told Vogue magazine: ''A princess should be sexy. She is young, she is beautiful - I would like to create something special for her, but nothing too bold. I would like to prove to the world that Roberto Cavalli can dress a princess.
''Maybe I would use a print, keeping it young, sophisticated and sexy. Just because you are a queen or princess it doesn't mean you can't be sexy.''
The 72-year-old fashion legend also discussed another one of fashion's best-loved icons, Victoria Beckham, branding her an ''actress of fashion'' because of how influential her personal style is.
Roberto revealed: ''Victoria Beckham - she is in my heart ... I remember when she asked me to design the Spice Girls costumes for the reunion in 2008, I was so surprised and pleased because I really didn't like the competition - Dolce & Gabbana.
''When someone wears a dress really well, I describe them as an actress of fashion, rather than a model. That's what Victoria is - an actress of clothes because she interprets what she wears.''