Throughout human history, seaweeds have been used as food, folk remedies, dyes, and mineral-rich fertilizers. Seaweeds as nutraceuticals or functional foods with dietary benefits beyond their fundamental macronutrient content are now a major research and industrial development concept. Nutritional studies on seaweeds indicate that brown and red seaweeds possess a good nutritional quality and could be used as an alternative source of dietary fiber, protein, and minerals. In this chapter, some of the seaweed-based nutraceuticals components like protein, amino acids, polysaccharides, vitamins, and minerals are described in a precise manner.