Fa la la la la la la la lovely!
The 33-year-old actress wore a strapless royal purple Vivienne Westwood column dress with delicate draping at the scooped neckline.
She capped off the outfit with long mermaid waves and a fresh, dewy makeup look.
We love this color on Katie, and it's good to see her adding a bit more drama and glamor into her style.
Though there's nothing groundbreaking here, Miz Holmes looks absolutely gorgeous, and sometimes that's all you need!