With the advancement of medicine, installing stents to replace blocked blood vessels has become a very popular surgery. However, restenosis, i.e., the re-narrowing of blood vessels following angioplasty or stent placement, remains a significant clinical challenge, with historical rates of 50 % for balloon angioplasty and 30 % for stents. Although drug-coated stents have reduced restenosis to 5 %–10 %, coronary artery disease continues to threaten patients' lives. In this study, we investigated the potential of plasmon-activated water (PAW) to effectively prevent vascular restenosis. PAW was prepared by irradiating gold nanoparticles with resonant light, disrupting hydrogen bonds in the water and forming smaller clusters with reduced affinity. In vitro and in vivo experiments demonstrated that PAW enhanced human umbilical vein endothelial cell (HUVEC) viability and migration. In vivo , balloon angioplasty was performed on carotid arteries of Sprague-Dawley rats to simulate intimal injury. An analysis revealed that PAW significantly inhibited intimal hyperplasia and downregulated CD44 and IL18 gene expressions while reducing oxidative stress markers like malondialdehyde (MDA). Moreover, PAW increased the abundance of anti-inflammatory Limosilactobacillus in the gut microbiota, which was responsible for the observed marked depression of restenosis in PAW-consuming rats. These findings suggest that PAW's distinct anti-inflammatory, antioxidant, and endothelial cell-promoting properties make it a promising candidate for reducing restenosis and improving cardiovascular outcomes.