Endophytic fungi, a symbiotic aid for plants in adverse conditions. These fungi play a crucial role in enhancing plant resilience to biotic stresses like herbivory, pathogen attacks, and competition. This symbiotic relationship is crucial for the adaptation of plants to diverse and challenging environments. Plant-endophytic fungi interaction has multiple modes of communication, such as chemical signaling, physical interactions, and symbiotic interactions. The communication mechanisms employed by endophytic fungi to mediate stress tolerance involve complex signaling networks that include molecular exchanges between the fungi, the plant, and associated microbiota. These interactions typically occur through the production of secondary metabolites, hormones, and proteins, which influence plant defense mechanisms and facilitate the maintenance of plant homeostasis under stress conditions. This review investigates the timeline of plant endophytic fungi as a symbiont to deal with biotic stress. This review highlights the diverse communication strategies employed by plant endophytic fungi to mediate biotic stress resistance, providing insight into the molecular and physiological mechanisms that underpin these relationships. Understanding these mechanisms opens new avenues for utilizing endophytic fungi in sustainable agricultural practices, where they could be employed as natural biocontrol agents to promote plant health and productivity in the face of biotic stressors.