The fabrication of nanogenerators requires more innovative materials for their optimal performance and superior efficiency. Over the past few years, biopolymers have become an interesting material for the energy field due to their inherent properties like biocompatibility, mechanical strength, and dielectric properties. This book chapter summarizes the advancements in the development of nanogenerators based on biopolymers, with special focus on cellulose, chitosan, silk fibroin, and alginate. The chapter begins by introducing the different types of nanogenerators, and in the subsequent sections, it gives more importance to piezoelectric and triboelectric nanogenerators for energy harvesting applications. The mechanism of piezoelectric and triboelectric nanogenerators is briefly explained in the chapter. The source, structure, and mechanism of charge generation in different biopolymers are also discussed. The chapter also includes the main fabrication techniques used for nanogenerators. Finally, the major applications of biopolymer-based nanogenerators in different fields like energy harvesting, healthcare monitoring, gas sensing, and self-powered devices are illustrated.