Biointegrated electronics can serve as versatile platforms to continuously monitor the evolving dynamic human physiological state and to evaluate the overall health status. Conventional constituent materials of biointegrated electronic devices cause the biocompatibility issue owing to the large mechanical mismatch with soft and curvilinear biological tissues. Emerging soft elastic conductive nanocomposites, composing of conductive nanofiller percolation networks throughout insulating polymer matrices, can bypass this issue due to their intrinsic stretchability inherited from polymer matrices. Given this intriguing attribute, soft conductive nanocomposites have been applied for many wearable and implanted applications.