Tweeting her excitement over the famous designer's classy soiree, Miss Tisdale wrote prior to arrival, "Super excited for the Mui Mui party tonight!"
Also joining in on the festivities were more-seasoned Hollywood gals including Malin Akerman and Diane Kruger, along with model.actress Kate Mara.
Being the youngest of the group, 14-year-old Miss Steinfeld partook in the MIU MIU festivities thanks to her role as face of the brand - as she recently shot their Autumn/Winter 2011 collection campaign.
Talking about the experience, Hailee told press, “It’s so much fun to have the chance to work with such a gifted designer and wear these incredible clothes. I feel so lucky to be a part of it."