AbstractDeveloping polymer‐based piezoelectric materials with multistimulus responsiveness is highly desirable for advancing multi‐source energy harvesting in wearable electronics. Inspired by the multifunctionality of muscle fibers, a nanostructure interface engineering strategy to create piezoelectric polymeric nanoheterostructures (PNHs) with remarkable responsiveness to both mechanical and nonmechanical contactless stimuli is introduced. Through precise interfacing of polymer nanofibers with nanoparticles via multiscale‐regulated interface electrostatic and chemical interactions, the study achieves a controlled assembly of stabilized and hierarchically organized nanoheterostructures featuring unique interface‐confined configurations. These configurations induce in situ stabilized dipole orientation and significant geometric stress nano‐confinement at interfaces, crucial for amplifying electricity generation. Compared to conventional polymer nanocomposites, engineered PNHs exhibit dramatically enhanced piezoelectricity, boasting a higher sensitivity of 1065 mV kPa−1 and piezoelectric coefficient of 76.2 pC N−1. Furthermore, PNHs demonstrate superior thermo‐actuated electricity generation under temperature fluctuations through cooperative spontaneous polarizations of constituent nanostructures, yielding a higher pyroelectric coefficient of 3.13 µC m2K−1. Additionally, the design enables photothermally‐activated switchable electricity generation and light‐energy harvesting, achieving a photo‐electric conversion efficiency tenfold higher than nanocomposites. This effective and versatile approach inspires the development of multi‐responsive nanogenerators for multi‐energy harvesting and self‐powered multistimulus‐sensing applications.