With the rise in global demand for natural, sustainable, and preventive healthcare solutions, the nutraceutical industry is undergoing a rapid transformation. However, there remains a significant gap in consolidated knowledge about the role of microalgae, which are recognized as one of the most diverse and sustainable natural resources and have become crucial in the development of therapeutics and functional foods. Among them, Haematococcus pluvialis is recognized as a scalable source of high-value compounds— astaxanthin which has the highest antioxidant property. This chapter provides an in-depth exploration of microalgal astaxanthin with special emphasis on its therapeutic application and incorporation into functional food systems. It discusses the growth phases of H. pluvialis, triggers for the astaxanthin biosynthesis pathway, optimization of culture conditions for enhanced biomass and pigment production while highlighting the biochemical composition of microalgal species. The economical demand of microalgal production systems is addressed to highlight commercialization challenges and opportunities. By bridging the gap between algal biotechnology and health sciences, this review underscores the potential of H. pluvialis-derived astaxanthin as a key component of future therapeutic and functional food products, supporting a shift toward preventive, natural, and sustainable healthcare solutions.