Elle was watched on by her older sister, Dakota Fanning, who shared a video of the milestone moment on Instagram.
"I can see you hiding your smile!" Dakota wrote in the caption. "I love you and am so proud of you!"
After the show, the 19-year-old actress and Miu Miu ambassador posed alongside fellow celebrity fans of the brand. Here, Elle is pictured with Rami Malek, Rachel Brosnahan, Melanie Laurent, Elle Fanning, Miuccia Prada, Stacy Martin, Rebecca Dayan, Rowan Blanchard, Paul Dano, Zoe Kazan, David Harbour and Alison Sudol.