Climate change is driving a rise in the contamination of crops by mycotoxins, threatening global food security. If agrochemical use is to be reduced, environmentally friendly antimycotoxin solutions are urgently needed. This study aims to elucidate the antifungal and antimycotoxin modes of action of stilbenoid molecules from vine by-product extracts against Fusarium graminearum, the primary causal agent of Fusarium head blight in wheat and a main producer of type B trichothecene (TCTB) mycotoxins. E-resveratrol (RES), a monomer, and E-vitisin B (VIT), a tetramer, were selected as the targeted stilbenoids due to their predominance in vine extracts. VIT (8 µM) showed greater efficacy than RES (35 µM) in inhibiting spore germination, biomass production, and TCTB yield. To better understand their modes of action, a multi-omics approach combining mRNA-seq-based transcriptomics and LC-MS/MS-based untargeted metabolomics was employed. mRNA-seq data evidenced that VIT exposure altered the expression of nearly half of F. graminearum genes, whereas RES induced only minimal transcriptomic changes. Integrated with metabolomics data, our findings suggest that VIT’s modes of action involves: (1) disruption of the fungal cell wall and plasma membrane via downregulation of sphingolipid metabolism, (2) inhibition of sporulation and hyphal growth, and (3) both direct and indirect interference with TCTB biosynthesis. These findings support the potential of viniculture waste-derived compounds as biofungicides, offering a dual benefit of reducing cereal mycotoxin contamination and valorising underused vine biomass.