The UNESCO World Engineering Day 2022 theme says, “Build back wiser, Engineering for the future.” In this vein, it’s essential to champion sustainable solutions to SDG 7, developing affordable and clean energy for the next generation. Researchers are making a concerted effort to develop long-term alternatives to our over-reliance on the production and usage of fossil fuels. In recent years, electrochemical energy storage devices like batteries and supercapacitors have been seen as the next step in energy storage. These technologies use materials made of carbon as their electrode. Carbon derived from biowaste/biomass presents a renewable approach to sustainable electrode production for electrochemical energy storage technologies. Biowaste/biomass and its by-products are naturally occurring and present in significant amounts in several forms. Carbonaceous materials derived from biowaste/biomass have distinct chemical, structural, and mechanical features, including high surface area, tunable structure, availability, renewable nature, low cost, and eco-friendliness. This chapter discusses the application of biowaste/biomass in electrochemical energy storage devices such as batteries and supercapacitors. The chapter also addresses electrochemical energy devices, their working principles, and their limitations. Throughout the chapter, efforts are made to suggest how biowaste/biomass can help to improve properties such as energy density, power density, cycle life, and safety of these electrochemical energy devices.