Many biotic and abiotic environmental factors influence plant growth. One of the essential components supporting plants is the epiphytic flora. Epiphytic microorganisms, which can establish symbiotic, neutral, and mutualistic relationships with the plant, colonize the entire surface of the plant, from roots to flower organs and seeds. They protect their hosts against plant pathogens and predators, stress resistance, promote growth and development, and virtually all metabolic events. Although the importance of a healthy microbiome in soil and plants has been proven, the organisms involved and their responses to environmental dynamics are still the subject of research. Studies on the agricultural potential of nanoparticles have shown that, while supporting plant growth, they also increase plant resistance to biotic and abiotic stressors. The relationship of these molecules, which can be synthesized in an eco-friendly way by green synthesis and whose numerous benefits have been identified, with epiphytic flora is still a new and incomplete field. The effects of nanoparticles change when synthesized by members of the epiphytic flora, and the effects of nanoparticles synthesized in any way on epiphytic flora are still unclear. Studies show that after the application of various metal or metal oxide nanoparticles, changes occur in the composition of epiphytic microflora in plants and an increase in the adaptation of beneficial microorganisms, but there is also evidence that this flora may lose some of its members. In this chapter, the effect of nanoparticles synthesized by epiphytic flora and produced by green synthesis on plant growth, as well as recent studies on the effects of these particles on epiphytic flora, are included.