Chronic diseases currently account for majority of all incidences and deaths caused by human diseases worldwide. Furthermore, the incidence rates of several major chronic diseases such as cardiovascular disease, cancer, obesity, and diabetes are expected to continuously increase in many countries for a while. Therefore, chronic diseases remain a profound impact for individual health, health care cost, and public health strategy of people worldwide. Some microalgal pigments may directly counteract the development of the chronic diseases. Fucoxanthin (Fx), a highly polar carotenoid, is present abundantly in microalgae and edible brown macroalgae. Fx has been characterized as a safe compound without remarkable adverse events for human and rodents. Recently, drink-, edible oil-, emulsion-, encapsulation-, or powder-based Fx products prepared from biological materials have been successfully commercialized as food additives, as well as in cosmetic and pharmaceutical applications. In the 1990s, only few reports on the beneficial and anti-cancer effects of Fx are available in vitro and in vivo. The underlying mechanisms were largely unknown. From the 2000s to 2020s, the beneficial effects of Fx have been prevalently shown on prevention of various chronic diseases: cancer, cardiovascular disease, cerebrovascular disorder, hypertension, arteriosclerosis, airway disease, obesity, diabetes, liver and kidney injuries, inflammatory bowel disease, neurodegenerative disease, among others. In addition, their preventive mechanisms are also being elucidated. This chapter provides the vast potential of Fx in preventing chronic diseases from 1990 to 2024.