Objective To investigate the correlation between the combined assessment of preoperative 5-factor modified frailty index(mFI-5)and Naples prognostic score(NPS)with overall survival in patients with unresectable hepatocellular carcinoma(uHCC)following interventional therapy.Methods A retrospective cohort study enrolled 292 patients with uHCC who underwent interventional therapy at the Department of Hepatobiliary Pancreatic Surgery of the Second Affiliated Hospital in Army Medical University from October 2017 to December 2021.Patients were stratified into high-risk and low-risk groups based on mFI-5(≥1),NPS(≥3),and CONUT(≥4)scores.Propensity score matching(PSM)was performed to balance baseline characteristics(post-matching n=186).The primary endpoint was overall survival(OS),analyzed using Kaplan-Meier curves with log-rank tests.The predictive performance of combined indicators was evaluated by receiver operating characteristic(ROC)curves,and prognostic factors were assessed via Cox regression analysis.Results After PSM,baseline characteristics(including age,tumor markers,and treatment-related parameters)showed no significant differences between the two groups.Survival analysis demonstrated a 2.252-fold higher risk of death in the mFI-5 plus NPS high-risk group(95%CI:1.60～3.18,P<0.001).The combination of mFI-5 and NPS scores yielded an area under curve(AUC)of 0.718 for predicting 3-year overall survival,significantly outperforming either index alone(P=0.007).Multivariable Cox regression analysis identified that dual positivity for mFI-5 and NPS(HR=1.46;95%CI:1.01～2.11,P=0.044),portal vein tumor thrombosis(HR=1.49;95%CI:1.03～2.16,P=0.035),tumor diameter>5 cm(HR=2.01;95%CI:1.27～3.17,P=0.003),Barcelona clinic liver cancer(BCLC)stage C disease(HR=2.05;95%CI:1.37～3.07,P<0.001)were independent predictors of poor prognosis.Postoperative combination targeted therapy and immunotherapy was associated with significantly reduced mortality risk(HR=0.57;95%CI:0.39～0.81,P=0.002).Conclusion The combination of mFI-5 and NPS scores is significantly associated with overall survival in patients with unresectable hepatocellular carcinoma(uHCC)undergoing locoregional therapy,providing a validated tool for clinical risk stratification and personalized treatment planning.