Plants produce a diverse array of secondary compounds to safeguard themselves against attacking pathogens. While some of these secondary products have direct utility as medicines, others may not have pharmacological activity in their native state. However, plant cells, tissues, organs, and enzymes can catalyze the conversion of pharmacologically inactive compounds into physiologically or pharmacologically active compounds. This process of transforming inactive compounds into active ones through enzymatic catalysis is known as biotransformation. Various chemical compounds such as alkaloids, aromatic compounds, coumarins, steroids, and terpenoids undergo biotransformation via reactions including acetylation, esterification, glycosylation, hydrogenation, hydrolysis, hydroxylation, isomerization, methylation, oxidation, and reduction. This chapter recapitulates the recent literature and developments in the field. The invigorating results obtained thus far enhance our knowledge on the production of new compounds of pharmaceutical importance and emphasize the need to accelerate research in this area. Furthermore, we conclude that co-culturing suspension cultures or tissues from two different plant species can enhance biotransformation efficiencies, thereby aiding the pharmaceutical industry in achieving low-cost production using green chemistry technology.