This chapter focuses on the remarkable bioactive compound phycocyanin, which is sourced from microalgae and cyanobacteria. It thoroughly explores the intricate aspects of phycocyanin, revealing its unique biochemical properties and highlighting its significant potential in various biological activities. Phycocyanin is notable for its ability to defend against microbes, alleviate inflammatory responses, and exhibit robust antioxidant capabilities, making it a versatile compound with promising applications. The exploration guides us through the complexities of extracting and purifying phycocyanin, investigating innovative techniques to efficiently obtain this valuable compound while addressing the associated challenges. As the chapter navigates through the applications of phycocyanin, it illuminates its role across diverse fields, from pharmaceuticals to cosmetics, thereby demonstrating its versatility and importance.