Astaxanthin (ASX) is a xanthophyll carotenoid, naturally synthesized by Algae, Yeast, and bacteria. They are not just a powerhouse of antioxidant properties but also possess anti-inflammatory and other bioactive properties. Haematococcus pluvialis is the potential ASX source and shows powerful regulation on many health diseases. Over the decades, numerous studies have emphasized its importance in many human health diseases such as neurodegenerative disorders, cardiovascular diseases, Alzheimer, Parkinson, skin allergies, COVID-19, and many more. The present review discusses available evidence on the functional activities of ASX in various diseases and summarizes the potential factors involved in ASX response and highlights the potential implications.