Biocatalysis has emerged as powerful and sustainable alternative to traditional chemical synthesis techniques in pharmaceutical manufacture of Active Pharmaceutical Ingredients (APIs). In light of mounting global demand for green chemistry and circular bioeconomy, biocatalysts, especially enzymes, have been crucial in reshaping pharmaceutical production processes. They operate under mild conditions, reducing the use of hazardous chemicals, catalyst and solvents, less byproduct formation due to high regio-, chemo-, and enantio-selectivity thus increasing yields and quality with minimized environmental impact. This chapter delves into the transformative role of biocatalysis in API synthesis by presenting case studies of successful enzymatic conversions, underscoring its environmental sustainability, industrial scalability, economic and technological advantages, and contribution to the circular bioeconomy.