High-fat diets (HFD) exacerbate intestinal health risks in aquaculture. This study evaluated effects of dietary sulforaphane (SFN) supplementation on intestinal morphology, biochemistry, microbiota, and metabolism in Yellow River carp (Cyprinus carpio haematopterus) fed HFD. Five isoprotein diets diets were formulated: control (CN, 6 % lipid), HFD (12.29 % lipid), and HFD with 10 (HS10), 15 (HS15), or 20 (HS20) mg/kg SFN. Results demonstrated that HFD induced marked intestinal inflammation featuring villi deformation, oxidative stress, epithelial exfoliation, mitochondrial swelling, significantly elevated pro-inflammatory cytokines (TNF-α/IL-1β/IL-6; p < 0.05), and downregulated tight junction protein genes (Occludin/ZO-1/Claudin-3; p < 0.05), concomitant with microbial dysbiosis (Proteobacteria dominance>70 %, reduced Cetobacterium) and disrupted metabolic pathways (amino acid imbalance). SFN supplementation significantly enhanced antioxidant enzyme activities (SOD/CAT/GSH-Px, p < 0.05), peaking in HS15, which also exhibited minimized pro-inflammatory cytokines and maximized tight junction expression (p < 0.05). Furthermore, 16S rRNA gene sequencing of the gut microbiota indicated that SFN restored microbial homeostasis, notably by increasing the abundance of Cetobacterium. Metabolomic analysis based on KEGG enrichment revealed that these beneficial effects were associated with the activation of FoxO signaling, enhanced lysosomal function, and upregulation of coenzyme A biosynthesis. Critically, HS15 demonstrated optimal efficacy across all parameters. Therefore, 15 mg/kg SFN is identified as the optimal dose to ameliorate intestinal health in Yellow River carp, providing a theoretical basis for functional aquafeed development.