To achieve conformal and monolithic integration between biological tissues and electronic systems, the development of high- performance soft conductors is essential. We have engineered functional nanocomposites and nanomembranes by synthesizing and assembling shape-controlled nanomaterials and strategically embedding them within soft elastomers. As a result, we developed nanocomposites and nanomembranes with outstanding electrical and mechanical properties, including high stretchability (^(M)Science, 2021), strain-insensitivity (^(ⅰ)Advanced Materials, 2022), and metal-like conductivity (^(ⅱ)Advanced Materials, 2023), and isotropic electrical properties (^(ⅲ)Advanced Materials, 2025). Furthermore, we synthesized core-shell nanowires for longer material stability (^(ⅳ)Nature Nanotechnology, 2018) and demonstrated their applicability in soft bio-interfacing for heart (^(ⅴ)Science Translational Medicine, 2016) and peripheral nerve (^(ⅵ)Advanced Materials, 2021 ). By bridging nanoscale material innovation and biomedical device application, our research aims to advance the field of biomedical engineering.