The escalating threat posed by plant pathogens to global agricultural productivity requires the development of sustainable and environmentally friendly control strategies. This chapter provides an in-depth review of microbial biocontrol agents as formidable defenders against plant pathogens. The introduction highlights the critical importance of plant disease control and lays the foundation for understanding biocontrol in agriculture. The chapter explores the diversity of microbial biocontrol agents, encompassing fungi, bacteria, yeast, and viruses, with emphasis on their potential contributions. An important part is devoted to the discovery of the mechanisms of action employed by these microbial defenders. Detailed discussions of competition, parasitism, antibiosis, and induced systemic resistance (ISR) provide valuable insights into how these agents suppress pathogen growth and enhance plant immunity. Choosing the appropriate microbial inoculants is a critical factor determining the success of a biocontrol program, followed by the challenge of deploying them effectively in the field while ensuring consistent performance. This chapter reviews various microbial bioformulations and their application methods, such as seed treatment, soil drenching, and foliar sprays. It examines challenges in microbial biocontrol, including environmental factors and commercialization barriers. Emerging trends and technological advances are also discussed, offering insights into improving the effectiveness of these biocontrol strategies. The conclusion highlights the potential of microbial biocontrol as a sustainable component of modern agriculture. This chapter serves as a guide for researchers, practitioners, and policymakers interested in using microorganisms to reduce pathogen impact and enhance agricultural production.