<p>The global agricultural system is continuously facing many threats that arise from phytopathogens, which pose a serious challenge to food security worldwide. Synthetic biology approaches and advances in biotechnology have developed various methods to control these diseases, they are not yet fully effective in protecting plants from all phytopathogens. In this context, nature offers an alternative solution through plant associated microbiome. These beneficial microorganisms play a crucial role in mediating plant survival under biotic stress by influencing host immunity and metabolic responses. A better understanding of plant–microbe interactions at both genetic and metabolite levels is important. These interactions are controlled by complex regulatory networks and studying them will help us use their full potential. Consequently, research is expanding into how environmental factors, specifically light, influence plant physiology, immunity and secondary metabolism. Recent studies have suggested that light not only shapes plant immunity but also modulates the accumulation and behaviour of associated microbial community, therefore influencing the outcome of biotic stress interactions. This review focuses on the role of light as a regulatory signal in plant–microbe interactions under biotic stress. It explains how light controls secondary metabolite production and plant defence mechanisms. It also highlights how light responsive pathways can be used to develop disease-resistant and climate smart crops. The integration of photobiology with microbiome research may open new approaches for sustainable and resilient agricultural systems. This approach can help address the challenges posed by emerging phytopathogen.</p>