The 29-year-old showed off the ink, which features the initials CD, in an ad for her new Benzo sunglasses campaign with eyewear brand Prive Revaux.
"So excited to share this with you guys," she wrote on Instagram alongside the photo, in which she showed off the body art. "My new collection with @priverevaux is here."
Fans were quick to point out the detail, with one noting "I spy caras initials," while another remarked "Tattoo CD."
Benson and the model began dating last year (2018).