During the last decade green synthesized cerium oxide nanoparticles (CeO 2 NPs) attracted remarkable interest in various fields of science and technology. This review, explores the vast array of biological resources such as plants, microbes, and other biological products being used in synthesis of CeO 2 NPs. It also discusses their biosynthetic mechanism, current understandings, and trends in the green synthesis of CeO 2 NPs. Novel therapies based on green synthesized CeO 2 NPs are illustrated, in particular their antimicrobial potential along with attempts of their mechanistic elucidation. Overall, the main objective of this review is to provide a rational insight of the major accomplishments of CeO 2 NPs as novel therapeutics agents for a wide range of microbial pathogens and combating other diseases.