The interaction between plant pathogenic fungi and mycoviruses plays a significant role in ecosystems. Weakly virulent mycoviruses can significantly reduce the virulence and infectivity of plant pathogenic fungi. In some cases, fungal pathogens can even transform into beneficial endophytic fungi after viral infection. As a result, using weakly virulent mycoviruses as biocontrol agents become an emerging and promising strategy for controlling plant fungal diseases. In recent years, with the rapid development of environmental sampling and molecular biology techniques, research on mycoviruses has made significant progress, especially regarding the complex interactions among viruses, fungi, and plants. This review provides a comprehensive analysis of the research progress on plant-fungus-virus interactions and looks forward to the potential applications of this field in plant disease management.