The 35-year-old opted for a loose braid and a smokey eye for the Beverly Hills event on Thursday night.
She also posed for an over-the-shoulder photo to show off the backless gown.
Vonn recently made headlines when she opted for a completely sheer two-piece ensemble at a Fashion Week event in New York City in September.
At the Vanity Fair Best Dressed List party, the athlete walked the carpet in a sheer black crop-top with star detailing and a matching pant.
"I said YES!!! 💍❤️Can’t wait to spend the rest of my life with this crazy/kind/handsome/hyper/giving man #heputaringonit #isaidyes," Vonn captioned a video of the couple chatting about the major moment.
In July 2018, Subban gushed over his partner to Fox News.
“I haven’t met anyone who’s tougher than her yet,” Subban said of Vonn. “But what she’s gone through — just how she’s done it and how she’s managed to bounce back from those serious injuries and remain at the top, I don’t think I know another athlete that’s been as successful as she has pre-and-post injuries."
He continued: “It says a lot about her character, and now I get to see it every day — just how hard she works and how much she takes great care of herself."