Nanopolymers are a special class of nanomaterials that combine polymers with nanoscale features to provide improved mechanical, electrical, optical, chemical, and thermal properties. Nanopolymers have an essential role in our everyday life. They are used in clean energy harvesting due to their flexibility, biocompatibility, easy processability, lightweight, low cost, and friendliness. The innovative techniques have enabled scientists to synthesize nanopolymers with unique properties. Synthesizing nanopolymers and tailoring for desired properties broaden the application of nanopolymers. Nanopolymers are promising candidates for flexible and wearable energy harvesting devices. The flexible, self-powered, and wearable nanopolymer-based triboelectric and piezoelectric nanogenerators show outstanding performances in scavenging electrical energy from human body movement, wind energy, rain-drop energy, wave energy, and vibrational energy. It is crucial to tailor the properties of nanopolymers, such as the charge density, piezoelectricity, ferroelectricity, and dielectricity, to enhance the performance of nanopolymer-based energy harvesting devices.