Miley, 21, stunned in a jaw-dropping Tom Ford bondage-inspired dress, featuring a few strategically-placed strips of cloth to cover her chest. Besides all that, she appeared modest from the waist down in a long black skirt.
In addition to her wardrobe choice, Miley's hairstyle was also a point of attention, showing off a short, blonde punk rock-ish pixie cut. She chose this show-stopping outfit for a charity gala that she attended with her mother Tish Cyrus.
Meanwhile, Rihanna, 26, almost seemed to one-up the "Wrecking Ball" singer in a white Tom Ford dress with a dangerously high slit and purple sequins covering her bust.
The amfAR Gala, which benefits AIDS research, brought out a myriad of famous faces, including Lea Michele, Gwyneth Paltrow, January Jones, Kat Dennings and Beth Behrs --all who were a bit more clothed than Miley and RiRi.
This wouldn't be the first (or last) time we've seen Miley and Rihanna in scandalous styles. Here's a look back at some of RiRi's barely-there looks.