Postoperative complication III-V is closely related with hepatectomy-related mortality for hepatocellular carcinoma (HCC) patients. The aim of the study was to investigate the relationship between CONUTS and postoperative complication III-V. 1334 HCC patients who underwent hepatectomy were divided into two groups: high CONUTS group (early postoperative CONUTS ≥ 8, n = 659) and low CONUTS group (early postoperative CONUTS < 8, n = 675). The characteristics and clinical outcomes were compared and analyzed. Risk factors for postoperative complication III-V were evaluated by univariate and multivariate analysis. early postoperative CONUTS showed a good prediction ability for postoperative complication III-V (AUROC = 0.653, P < 0.001), with the cut-off value of 8. The high CONUTS group had higher incidence of postoperative pulmonary complications (12.0% vs 7.9%, P = 0.011), bile leakage (2.6% vs 0.9%, P = 0.018), intra-abdominal hemorrhage (4.9% vs 1.6%, P = 0.001), postoperative liver failure Grade C (3.6% vs 1.0%, P = 0.002), complication III-V (15.6% vs 6.2%, P < 0.001), length of ICU stay > 48 hours (9.4% vs 4.1%, P < 0.001) and mortality in 90 days (2.6% vs 0.4%, P = 0.001), longer period of postoperative hospitalization (10 (8-13) vs 9 (7-11) days, P < 0.001). Multivariable analysis revealed that early postoperative CONUTS ≥ 8 (OR = 2.054, 95%CI = 1.371-3.078, P < 0.001) was independently associated with postoperative complication III-V. Early postoperative CONUTS ≥ 8 was identified as a novel risk factor for postoperative complication III-V, and should be further evaluated as a predictive marker for who are to undergo liver resection.