The exploitation of naturally occurring polymers to engineer advanced nanocomposites and hybrid materials is the focus of increasing scientific activity, explained by growing environmental concerns and interest in the peculiar features and multiple functionalities of these macromolecules. Natural polymers, such as polysaccharides and proteins, present a remarkable potential for the design of all kinds of materials for application in a multitude of domains. This Special Issue collected the work of scientists on the current developments in the field of multifunctional biopolymer-based nanocomposites and hybrid materials with a particular emphasis on their production methodologies, properties, and prominent applications. Thus, materials related to bio-based nanocomposites and hybrid materials manufactured with different partners, namely natural polymers, bioactive compounds, and inorganic nanoparticles, are reported in the Special Issue Advanced Biopolymer-Based Nanocomposites and Hybrid Materials.