Persistent fungal pathogens remain a threat to global food security as these pathogens continue to infect crops despite different mitigating strategies. Traditionally, synthetic fungicides are used to combat these threats, but their environmental and health impacts have spurred interest in a more sustainable, eco-friendly approach. Endolichenic fungi (ELF) are a relatively underexplored group of microorganisms found thriving inside the lichen thalli. They are seen as promising alternatives for developing sustainable plant disease management strategies. Hence, in this study, a total of forty ELF isolates from two fruticose lichen hosts—Ramalina and Usnea, were tested and compared for their antagonistic activities against three economically important filamentous fungal pathogens—Colletotrichum gloeosporioides, Cladosporium cladosporioides, and Fusarium oxysporum. The results of the dual culture assay showed that all ELF isolates successfully reduced the growth of the three filamentous fungal pathogens with varying degrees, and with direct contact inhibition as the predominant trait among the endolichenic fungi. Comparing the antagonistic activities between the different endolichenic fungi from the two lichen hosts, ELF isolates from Ramalina generally demonstrated a higher percentage inhibition of growth of the test fungi as compared to ELF isolates from Usnea. This study underscores the importance of endolichenic fungi as an efficient biocontrol agent. Keywords: antifungal activity; fungal pathogen; lichen symbiosis; lichen-associated fungi; thalli.