The structural features of biological organisms have evolved through natural selection to provide highly tailored functions, inspiring numerous biomimetic and biological design strategies. A wide scope of untapped potential lies in harnessing the nanoscale architectural properties of natural biological materials to develop high-performance sensors. Herein, we report the development of an ultrasensitive chemical sensor that is based on the three-dimensional (3D) biomimetic templating of a structurally hierarchical butterfly wing. In conjunction with graphene sheet coating strategies, the porous 3D architecture enables highly selective detection of diabetes-related volatile organic compounds (VOCs), including a rapid response time (≤1 s), a low limit of detection (20 ppb), and superior mechanical properties. Taken together, the findings in this work demonstrate the promise of incorporating natural biological materials into high-performance sensors, with excellent potential for wearable and flexible sensors.