Background QRS duration (QRSd) is a marker of electrical remodeling in heart failure. Anthropometrics and left ventricular size may influence QRSd and, in turn, may influence the association between QRSd and heart failure outcomes. Methods and Results Using the prospective, multicenter, multinational ASIAN‐HF (Asian Sudden Cardiac Death in Heart Failure) registry, this study evaluated whether electroanatomic ratios (QRSd indexed for height or left ventricular end‐diastole volume) are associated with 1‐year mortality in individuals with heart failure with reduced ejection fraction. The study included 4899 individuals (aged 60±19 years, 78% male, mean left ventricular ejection fraction: 27.3±7.1%). In the overall cohort, QRSd was not associated with all‐cause mortality (hazard ratio [HR], 1.003; 95% CI, 0.999–1.006, P =0.142) or sudden cardiac death (HR, 1.006; 95% CI, 1.000–1.013, P =0.059). QRS/height was associated with all‐cause mortality (HR, 1.165; 95% CI, 1.046–1.296, P =0.005 with interaction by sex p _interaction =0.020) and sudden cardiac death (HR, 1.270; 95% CI, 1.021–1.580, P =0.032). QRS/left ventricular end‐diastole volume was associated with all‐cause mortality (HR, 1.22; 95% CI, 1.05–1.43, P =0.011) and sudden cardiac death (HR, 1.461; 95% CI, 1.090–1.957, P =0.011) in patients with nonischemic cardiomyopathy but not in patients with ischemic cardiomyopathy (all‐cause mortality: HR, 0.94; 95% CI, 0.79–1.11, P =0.467; sudden cardiac death: HR, 0.734; 95% CI, 0.477–1.132, P =0.162). Conclusions Electroanatomic ratios of QRSd indexed for body size or left ventricular size are associated with mortality in individuals with heart failure with reduced ejection fraction. In particular, increased QRS/height may be a marker of high risk in individuals with heart failure with reduced ejection fraction, and QRS/left ventricular end‐diastole volume may further risk stratify individuals with nonischemic heart failure with reduced ejection fraction. Registration URL: https://Clinicaltrials.gov . Unique identifier: NCT01633398.