Increasing health and environmental issues caused by chemical pesticides and fertilizers have spurred the adoption of sustainable alternatives in agriculture. Fungal secondary metabolites are the most important alternatives when compared to conventional agrochemicals. They can be used as eco-friendly substitutes in place of several other sustainable biopesticides, biofertilizers, and biocontrol agents as a highly promising solution for a sustainable agriculture. The bioactive chemicals generated by filamentous fungi serve a variety of purposes, such as managing pests, diseases, and promoting plant development. The intricate uses of secondary metabolites produced by fungi in the agricultural industry are discussed in this chapter. Examining the case studies provides crucial insights into practical approaches against disease and pest prevention. Mechanisms related to antagonistic interactions, competition, and the initiation of host defense systems are also studied. Furthermore, the section about mycorrhizal fungi will emphasize on how they aid in nutrient absorption, soil health promotion, and plant development, particularly in relation to sustainable agricultural systems. Genetic engineering and fermentation technologies are two recent innovations that will have a major influence on improving the production of fungal metabolites and, in turn, on raising agricultural productivity while reducing environmental impact.