Rapid advances in artificial intelligence, robotics, and remote healthcare have increased the demand for sustainable and high-performance wearable sensors. Triboelectric devices are gaining traction due to their self-powered operation capability and potential as wearable energy harvesters. Skin-interfaced triboelectric sensors (SITSs) can detect various mechanical signals and monitor physiological signals in real-time. Biopolymer-based SITSs are ideal for skin-interfaced applications since they are biocompatible and biodegradable. This review focuses on the recent advancements of SITS made from biocompatible polymer materials, such as plant-based, animal-based, and synthetic polymers, and highlights their potential for various applications, including human–machine interface (HMI) and physiological sensing. In addition, the fundamentals, challenges, and prospects of SITS based on biocompatible polymers are discussed.