Actinobacteria are the prokaryotes with the greatest ecological and economic significance. Their adaptability in terms of physiology and metabolism accounts for their vast distribution in nature. A variety of settings, including terrigenous, marine, aquatic, airborne, and extreme ones, host them. Marine actinobacteria are known to be a prospective source of new bioactive compounds. Mangroves are the most productive and fertile marine environment, because of their immense microbial diversity and unique ecophysiological characteristics. Researchers have discovered numerous new actinobacteria from mangrove environments around the world and investigated their potential for bioprospecting. This chapter will delve into the exploratory investigations conducted to know the diversity and global distribution of actinobacteria in mangrove ecosystems. In order to fully understand mangrove actinobacteria and maximize their potential for human benefit, this chapter aims to identify the knowledge gaps.