Gut microbiota dysbiosis is increasingly recognized as an upstream contributor to chronic low-grade inflammation and atherosclerosis (AS). Disruption of microbial homeostasis may impair intestinal barrier integrity, increase exposure to pro-inflammatory microbial products and metabolites, and reduce protective metabolites such as short-chain fatty acids (SCFAs), thereby activating innate immune signaling and sustaining vascular inflammation. Current evidence indicates that gut dysbiosis promotes atherosclerosis mainly through three interconnected processes: metabolite imbalance, barrier dysfunction with microbial translocation, and systemic immune reprogramming. Clinical studies have linked gut-derived biomarkers, particularly trimethylamine N-oxide (TMAO) and lipopolysaccharide (LPS)-related signals, to atherosclerotic burden and adverse cardiovascular outcomes, while experimental studies using fecal microbiota transplantation, probiotics, antibiotics, and gene-deficient models support a contributory role of the gut-immune-vascular axis. Emerging interventions, including dietary modulation, pharmacological repurposing, and microbiome-targeted therapies, may attenuate gut-derived chronic inflammation and offer new strategies for AS prevention and treatment. However, heterogeneity across studies and the limited causal evidence in humans warrant cautious interpretation. Overall, gut dysbiosis-driven chronic inflammation represents a biologically meaningful and potentially modifiable pathway in atherosclerosis.