As the worldwide population keeps rising dramatically, the demand for food production has increased, highlighting the need for sustainable strategies and bio-based alternatives to improve agricultural crop productivity. The endophytic microbial communities, which reside within plant tissues, have been suggested as a promising, eco-friendly alternative for improving plant health and productivity. Among these, Streptomyces spp., a crucial microbial genus known for producing a diverse range of bioactive secondary metabolites, has received considerable attention from the scientific community. This chapter is compiled to accommodate the recent advances in understanding the diverse roles of endophytic Streptomyces spp. in improving plant health. In this chapter, they have been described as the ‘probiotics’ for improving plant health, particularly under stressful environments (both biotic and abiotic). The possible mechanisms, through which they promote plant growth, such as the synthesis of PGRs (plant growth regulators), the enhancement of nutrient availability and their potential as biocontrol agents against biotic stresses, have been described in detail. Furthermore, endophytic Streptomyces enhance plant tolerance to various abiotic stressors, including heavy metal pollution, drought and salt, by modulating host gene expression and improving physiological resilience. The potential of endophytic Streptomyces as a next-generation bio-inoculant, paving the way to achieve sustainability in agro-ecosystems, has also been discussed. Overall, the chapter provides the readers with a comprehensive overview of the potential role of important endophytic Streptomyces spp. as probiotics for plant health promotion as an alternative elixir for improving sustainability in farming systems.