Adverse impacts on the ecosystem and human health due to the generation of toxic byproducts are major limitations of traditional methods such as physical and chemical nanoparticle (NP) synthesis. Hence, biosynthesis of nanoparticles has become a hot spot of research in the past decade as it offers an effective alternative to conventional synthesis methods. Green synthesis of nanoparticles from biogenic sources such as plants, bacteria, fungi, algae, and actinomycetes is more attractive due to their simplicity, cost-effectiveness, and ease of large-scale production. “Myconanotechnology” is an emerging field that utilizes fungal biomass for the production of nanoparticles. Diverse fungal strains are widely utilized to produce NPs as they form eco-friendly bio-factories capable of converting metal ions into their zerovalent or nanoforms. A variety of enzymes and proteins present in fungi act as reducing agents in this process. Fungi outperform bacteria and other sources in nanoparticle synthesis due to enzyme secretion, extensive mycelia surface area, and unique cell wall properties aiding metal ion absorption and reduction. Various fungal species including Penicillium, Aspergillus, Alternaria, Neurospora, Fusarium, Chrysosporium, Cladosporium, Trichoderma, Candida, Cryptococcus, Pleurotus, Agaricus, Coriolus, Ganoderma, Verticillium etc. are widely employed in nanoparticle synthesis. Myco-nanoparticles aid plant disease control with eco-friendly nano-insecticides, nano-fungicides, nano-pesticides, and nano-fertilizers, boosting agricultural productivity. This chapter evaluates the fungal nanoparticle synthesis, optimal production conditions, and their agricultural use for enhanced yields and sustainable farming.