Biopolymers from renewable resources are often used in multiple fields, namely health, food, energy, and the environment, due to their intrinsic features, versatility, biocompatibility, and degradability. Besides, the widespread use of biopolymers also addresses concerns about environmental sustainability. Biopolymers derived from many sources, e.g., marine, plant, animals, have been used alone or combined to process membranes for multiple applications. Therefore this chapter addresses the fundamental features in terms of the intrinsic characteristics, main properties, and applications of biopolymers as membranes. Moreover, the market trend is also discussed.