Background Erectile dysfunction (ED) is a prevalent condition in men over 40 years of age and is strongly associated with metabolic syndrome, a cluster of metabolic abnormalities including obesity, hypertension, dyslipidemia, and insulin resistance. Objective To assess the association between metabolic syndrome and erectile dysfunction in men over 40 years and to identify independent predictors of ED severity in this population Methodology This cross-sectional study was conducted at the Institute of Kidney Diseases (IKD), MTI Peshawar, from May 1, 2023, to April 30, 2024. A total of 230 male patients aged 40 years and above were recruited. The National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria categorized participants based on the presence or absence of metabolic syndrome. ED severity was assessed using the International Index of Erectile Function (IIEF-5) questionnaire. Descriptive statistics were used to present continuous variables as mean ± standard deviation (SD) and categorical variables as frequencies and percentages. The chi-square test was applied to assess associations between categorical variables, while the independent t-test or Mann-Whitney U test was used to compare means. Binary logistic regression was performed to determine independent predictors of ED, with a p-value <0.05 considered statistically significant. Results The prevalence of moderate to severe ED was significantly higher in men with metabolic syndrome (61.2%) compared to those without (28.7%) (p < 0.001). Participants with metabolic syndrome had significantly higher BMI (30.8 ± 4.2 kg/m², p = 0.002), waist circumference (102.3 ± 8.1 cm, p = 0.001), fasting glucose (124.6 ± 22.5 mg/dL, p < 0.001), and triglyceride levels (178.4 ± 35.7 mg/dL, p = 0.003). Logistic regression analysis identified obesity (OR: 2.75, 95% CI: 1.52–4.96, p = 0.001), hypertension (OR: 3.21, 95% CI: 1.89–5.47, p < 0.001), and low HDL cholesterol (OR: 2.58, 95% CI: 1.44–4.63, p = 0.002) as significant predictors of ED. Conclusion This study confirms a strong association between metabolic syndrome and erectile dysfunction, with metabolic abnormalities serving as independent predictors of ED severity. The findings emphasize the need for early metabolic screening and lifestyle interventions in men over 40 to prevent or manage ED. Future longitudinal studies should evaluate the impact of targeted interventions on erectile function in this high risk population.