Stewart, 25, is featured wearing nothing but a single white towel draped over her body in the newest image from Testino's "Towel Series", an ongoing collection of photos that the snapper has been sharing on Instagram.
The black-and-white pictures typically feature the subject wearing a white towel, reported People magazine.
Previous celebrity subjects included Gigi Hadid and her then-boyfriend Cody Simpson back in March, model-turned-actress Emily Ratajowski, Amanda Seyfried, Selena Gomez and even Anna Wintour.