The demand for sustainable and environmentally friendly materials has led to significant advancements in biodegradable polymer nanocomposites. These innovative materials combine the biodegradability of natural and synthetic polymers with the enhanced mechanical, thermal, and barrier properties provided by nanoscale fillers. This chapter explores the development and applications of biodegradable polymer nanocomposites, providing a comprehensive understanding of the types of polymers used, nanofillers, and fabrication techniques. Key topics include the natural and synthetic biodegradable polymers, the roles of organic and inorganic nanofillers, and methods for synthesizing nanocomposites with desirable properties. Furthermore, we examine the mechanical and thermal performance, biodegradation profiles, and environmental impact of these materials, showcasing their potential in diverse fields. By analyzing current challenges and future research directions, this chapter aims to highlight the pivotal role of biodegradable polymer nanocomposites in advancing sustainable material science.