Over the past 30 years, the use of plant growth-promoting bacteria (PGPB) has gained significant relevance in agricultural microbiology worldwide due to their proven ability to enhance crop yields, preserve agricultural ecosystems, and reduce the impact of agrochemicals. Among PGPB, the genus Azospirillum has been identified in various regions across the globe, establishing itself as a true plant colonizer and a model PGPB. Until not many years ago, Azospirillum was not considered a true biocontrol agent due to the lack of evidence supporting mechanisms that could explain this function. However, growing scientific evidence now supports several mechanisms by which Azospirillum exerts biocontrol activity against phytopathogens and insects, while others remain to be fully understood. This chapter explores the background of Azospirillum as a biocontrol agent, the mechanisms it employs to suppress plant pathogens, the role of its polar flagellum flagellin as an emerging subject of study in the control of phytopathogens, methods of applying Azospirillum, and future projections for its use in plant disease management.