The Special Issue "Marine Anti-Inflammatory and Antioxidants Agents 2021" collected the latest research, both in vitro and in vivo, on natural compounds from a variety of deep-sea organisms with anti-inflammatory and/or antioxidant properties as potential candidates for new drug discovery, and more generally for the field of marine biotechnology. The research presented here discusses the potential benefits of certain peptides and proteins derived from oysters, blue mussels, and cyanobacteria, as well as the carotenoid pigment astaxanthin, which is found in a variety of marine organisms. This Special Issue has carved out an important space for crude extracts from marine products, such as microalgae and green algae, highlighting their potential benefits to human health. Finally, the Special Issue includes a review of the benefits of some natural compounds derived from the algal biome against inflammatory bowel diseases, as well as a research article identifying the presence of the OvoA gene in arthropods for the first time. Through an excursus of high-quality research, this Special Issue provides the entire scientific community with new tools and insights to catch a molecular treasure for human health from the sea.