The Lost In Translation star celebrated the appointment in Milan at the latest catwalk show from the duo, Independent Television News reports.
She said: "It's very exciting. It's a huge honour for me and it's a lot of fun.
"The sort of icing on the cake, so to speak, the lipstick on the cake."
Other stars attending the event included Eva Mendes, Naomi Watts, Claudia Schiffer and Freida Pinto.