Marine origin biopolymers are of great interest due to their chemical and biological diversity. In particular, chitin and chitosan have attracted attention as potential sources of valuable materials with a vast range of properties and characteristics. In fact, the importance of these polymers is found in a high number of publications in the literature, focusing on their preparation methodology, analysis of physicochemical properties and applications. Recent studies have emphasized the processing of chitin and chitosan aerogels using mainly supercritical fluid technology, sol–gel methodology and freeze-drying techniques. In this chapter, we review the processing methodologies used and discuss the different methodologies obtained. We also highlight the possibility of preparing functional aerogels with bioactive properties from these natural origin polymers.