The rising demand for personalized healthcare has accelerated the development of skin-interfaced sensors that arecapable of real-time physiological monitoring, early disease detection, and individualized health management. These devices enablethe continuous and high-fidelity tracking of diverse physiological signals, such as cardiac activity, muscle contractions, respiration,and temperature, by closely conforming to the complex and dynamic surface of the human skin. However, conventional sensors fabricatedfrom rigid and brittle materials have poor conformability, mechanical mismatch, and reduced user comfort, thus leading tounreliable signal acquisition and limited long-term usability. Soft conductive nanocomposites have emerged as a promising alternativeto conventional sensors. The nanocomposites provide tunable electrical conductivity, mechanical compliance, and biocompatibilityby integrating conductive nanofillers into stretchable elastomeric matrices. The filler composition, dispersion, and microstructure ofthese materials can be optimized to closely match the mechanical properties of the skin while maintaining stable electrical performanceunder deformation. This review provides a comprehensive overview of recent advances in soft conductive nanocompositesfor skin-interfaced physiological monitoring, organized by widely used nanoscale and microscale fillers including metallic, carbonbased,liquid metal, and ionic materials. Furthermore, this review examines how conductive fillers affect the percolation behavior andelectromechanical performance of conductive nanocomposites. We highlight representative applications in monitoring the electricaland mechanical form of physiological signals. Finally, we present future research directions aimed at advancing these materialstoward next-generation wearable and biointegrated electronics for personalized healthcare.