Algae, a diverse group of photosynthetic organisms, have emerged as a sustainable and valuable source of vitamins for nutraceutical applications. Utilizing unique metabolic pathways, they biosynthesize a wide spectrum of both water-soluble (B-complex and C) and fat-soluble (A, D, E, and K) vitamins. Microalgae species such as Chlorella, Spirulina, and Dunaliella are particularly remarkable, serving as rich repositories for compounds like β-carotene (provitamin A) and highly bioavailable vitamin B12. These vital nutrients are fundamental to human health, where they support immune function, enhance antioxidant defense, facilitate cellular metabolism, and promote bone health. Due to their bioavailability and natural origin, algal vitamins are increasingly being integrated into functional foods, dietary supplements, and therapeutic formulations. Furthermore, their cultivation requires minimal resources such as freshwater and arable land, making them a sustainable alternative for meeting global nutritional demands. This chapter summarizes the sources and biosynthesis of vitamins in algae, their health benefits, the influence of cultivation conditions on vitamin production, and their diverse nutraceutical applications. It underscores the potential of algae to address global vitamin deficiencies and advance preventive healthcare through innovative and sustainable approaches.