BACKGROUND: Inflammatory bowel disease (IBD) management remains challenging due to limited preventive strategies and the low bioavailability of therapeutic agents like resveratrol (RSV). While RSV exhibits anti-inflammatory properties, its preventive potential via gut microbiome modulation remains unexplored. METHODS: A murine colitis model was established using 2.5% DSS, with mice randomized into control (CON), DSS, therapeutic RSV treatment (RSV), and preventive RSV treatment (PRE) groups. Clinical outcomes, intestinal barrier integrity, inflammatory cytokines, macrophage polarization, TLR4/NF-kappaB signaling, and gut microbiota (16S rRNA sequencing) were systematically evaluated. RESULTS: Preventive RSV (PRE) outperformed therapeutic RSV across all metrics. PRE attenuated colitis severity by 51.4% (weight loss, P < 0.001 vs. RSV) and restored mucosal architecture (P = 0.048 vs. DSS). Mechanistically, PRE normalized barrier function via transcriptional (ZO-1: 56.7% of CON; Occludin: 14-fold induction vs. DSS) and protein-level recovery (ZO-1: 96.5% of CON, P = 0.02), suppressed pro-inflammatory cytokines (TNF-alpha: 80.8%; IL-6: 69.9%; IL-18: >96%, P < 0.001 vs. DSS), and promoted M2 macrophage polarization (CD206: 1.7-fold vs. CON, P = 0.02) through TLR4/NF-kappaB inhibition (53% TLR4 reduction vs. 15% with RSV, P < 0.001). Despite comparable alpha-diversity between RSV and PRE, PRE uniquely enriched barrier-protective taxa (Lactococcus, Muribaculum) and restored microbial amino acid biosynthesis. Crucially, PRE's efficacy despite low systemic bioavailability implicated microbiome-mediated "luminal priming" as its primary mechanism. CONCLUSIONS: This study redefines preventive RSV as a microbial ecosystem engineer that preemptively fortifies the gut against inflammation via microbiome-immune-metabolic crosstalk. By prioritizing ecological prevention over symptom suppression, our findings offer a transformative "food as medicine" strategy for IBD, highlighting RSV's potential as a chronotherapeutic agent to reshape clinical paradigms.