Lignin, a plentiful byproduct of paper industries and biorefineries, shows great promise for sustainable energy applications. Its low cost, carbon-rich structure, and biodegradability make it an appealing alternative to traditional materials in the development of high-performance energy storage and harvesting devices. This chapter examines its potential in next-generation supercapacitors and thermoelectric materials for the biomedical industry. Lignin-derived carbon materials offer a sustainable and high-performance alternative to traditional battery materials for supercapacitors in medical devices. These supercapacitors can be more efficient and environmentally friendly. Additionally, the chapter examines the role of lignin in thermoelectric materials, which are essential for improving energy harvesting in wearable and implantable medical devices. By fully utilizing the potential of lignin, significant advancements can be made in sustainable energy solutions for the medical field.