Background: In heart failure with reduced ejection fraction (HFrEF), implantable cardioverter-defibrillators (ICDs) are used for the primary prevention of sudden cardiac death, yet many patients never receive appropriate therapy, and left ventricular ejection fraction (LVEF) alone poorly discriminates who will. We investigated whether a cumulative electrical risk score (ERS) derived from the surface electrocardiogram is associated with appropriate ICD therapy. Methods: In this single-center, retrospective study, 205 patients with HFrEF who underwent ICD implantation for primary prevention were classified according to whether they had received appropriate ICD therapy. A modified eight-parameter ERS was calculated from the baseline electrocardiogram. Associations were assessed using receiver operating characteristic (ROC) analysis and logistic regression. Results: The ERS showed moderate-to-good discrimination (AUC 0.795; p < 0.001); a cut-off of 3.5 yielded 91% sensitivity and 71.4% specificity. After adjustment for age, sex, LVEF, cardiomyopathy etiology, BNP and device duration, the ERS remained independently associated with appropriate ICD therapy (adjusted OR 2.189; 95% CI 1.246–3.845; p = 0.006). Conclusions: A cumulative electrical risk score from the standard electrocardiogram was independently associated with appropriate ICD therapy and may add risk information beyond LVEF. These retrospective findings warrant prospective, multicenter validation.