Piezoelectric nanomaterials have many important and unique properties which make them suitable for a wide range of applications including consumer goods, motor vehicles, medical devices and scientific instrumentation. Vibrations, biomechanical motions, and waves are examples of ever-present mechanical energy in the environment. The small size and unique electrical and mechanical properties inherent in piezoelectric nanomaterials make them ideal for harvesting these renewable energy sources. ZnO nanostructures have been widely studied for energy harvesting due to their enhanced piezoelectricity and scalable, reproducible synthesis techniques. Single atomic layer MoS2 is an emerging material for energy harvesting due to the existence of piezoelectric properties not found in the bulk material. Bio-inspired piezoelectric materials such as peptide nanotubes have excellent mechanical properties and are promising candidates for nanogenerator devices. Many different nanogenerator architectures have been developed and steadily improving performance has led to their incorporation into self-powered nanodevice systems.