Metabolic syndrome (MetS) is a major risk factor for cardiovascular and chronic diseases. This study evaluated how genetic predisposition and lifestyle factors contribute to MetS risk. We analysed data from 4,987 Koreans aged ≥ 40 years with at least one ASCVD risk factor (2014-2017). A polygenic risk score for metabolic disease (PRSMetS) using eight metabolic phenotypes was used to categorise participants into high and low PRSMetS groups (top 7% vs. bottom 93%). Lifestyle factors, including obesity, physical activity, smoking, diet, and alcohol consumption, were assessed with a healthy lifestyle score. The associations of PRSMetS and lifestyle factors with MetS risk were evaluated. High PRSMetS was associated with a 1.31-fold higher risk of MetS (adjusted odds ratio [aOR], 1.31; 95% confidence interval [CI], 1.03-1.66). MetS prevalence increased stepwise with worsening lifestyle in both low and high PRSMetS groups. Compared to the 'low PRSMetS and ideal lifestyle' group, MetS risk was significantly higher in all other lifestyle groups, with the highest risk observed in the 'high PRSMetS and poor lifestyle' (aOR, 9.35; 95% CI, 4.41-19.83) group. Both genetic predisposition and lifestyle factors significantly influenced MetS risk. Maintaining healthy lifestyle habits mitigates MetS risk, even in individuals with high genetic susceptibility.