<p>Fungal metabolites play a dual role, acting both as disease-causing factors and as promoters of plant health. Secondary metabolites (SMs) and volatile organic compounds (VOCs) comprise a chemically divergent toolkit by which fungi regulate interactions with plants, microorganisms, and their environment. Pathogenic fungi harness toxins like trichothecenes, botrydial, and alternariol to suppress host immunity and drive colonization, while beneficial taxa like <i>Trichoderma</i> and <i>Penicillium</i> produce similar chemicals that stimulate growth, elicit systemic resistance, or suppress pathogens. Such dual use of chemicals is carefully regulated by biosynthetic gene clusters (BGCs), many of which are dormant and only activated by specific ecological cues. Recent discoveries highlight the ecological ubiquity of these metabolites, wherein the same molecule is employed as a virulence factor in one context and growth enhancer in another. Advances in genome mining, metabolomics, and CRISPR-based activation are beginning to reveal the vast pool of hidden metabolic routes, while volatile-mediated signalling highlights the non-contact nature of plant-fungal interactions. Here, we integrate current knowledge of the biosynthesis, regulation, and ecological function of fungal metabolites, with particular focus upon their dual role as allies and adversaries. Overall, the review proposes the adoption of a systems-based strategy that takes advantage of valued metabolites to suppress pathogenic activity and depend less on chemicals thereby making fungal chemical biology useful for developing sustainable agroecological practices.</p>