The phylum Mollusca comprises a large group of invertebrate animals and represents the second most diverse phylum in the animal kingdom in number of extant species, which live mainly in marine habitats. In the harsh oceanic environment, mollusk species, like bivalves (cockles, mussels, oysters, scallops and clams), cephalopods (squids, octopuses and cuttlefishes) and gastropods (snail and snail-like mollusks) have thrived for millions of years. The biological diversity and ecological success of mollusks have also resulted in a vast diversity of molecules they contain. Numerous mollusk species have been valuable food resources to obtain essential nutrients for generations in different cultures. Moreover, the body parts and tissues of bivalves, gastropods and cephalopods have been used in traditional and folk medicine for therapeutic purposes. Beyond the nutrient values of mollusks, unique substances that are biologically and pharmacologically active can be extracted and used in their pure form or as constituents of extracts and hydrolysates. These pure biochemicals and preparations encompass a variety of chemical classes and biomolecules, which include, but are not restricted to, bioactive lipids, polysaccharides, polypeptides and peptides, as well as secondary metabolites. Molluscan biomolecules possess, individually or in combination, therapeutic properties such as anticoagulant, antithrombotic, antimicrobial, anti-inflammatory, anti-hypertensive, anti-diabetic and anti-hyperlipidemic, cytoprotective, metal-binding and osteogenic, among others. These bioactivities are useful to promote health and alleviate chronic disease symptoms. Owing to a number of mollusk species that are amenable to aquaculture, mollusks rise as sustainable bioresources to supply active ingredients for cosmeceutical, pharmaceutical and, importantly, nutraceutical industries.