Wearable sensing technologies have witnessed rapid development in recent years due to their accessibility, functionality, and affordability. However, heat accumulation and electromagnetic interference in electronic components adversely affect the sensing performance and seriously damage human health. Herein, cellulose nanofibers (CNFs)-based composites with high thermal conductivity (TC) and excellent electromagnetic interference (EMI) shielding performance are prepared using CNFs as templates followed by coating with tannic acid non-covalent and 3-aminopropyltriethoxysilane covalent co-modified graphene nanoplatelets (denoted as mGNPs) through a simple electrostatic self-assembly method. The subsequent hot-pressing process yield order and layer mGNPs in CNFs-based composites with mGNPs distributed along the orientation and in close contact with CNFs, a fashion similar to the human nervous system. The resulting CNFs-based composites reveal a high TC of 136.2 W/(m·K) and a superior EMI shielding effectiveness of 105 dB. Thus, they are used as wearable sensors based on the triboelectric effect to monitor human health in real-time, as well as express emotion through Morse code. In sum, the proposed strategy provides an avenue to prolong the service life of flexible wearable sensors and ensure their safe use, promising for future wisdom in healthcare and smart robotics.