Purpose Considering the initial treatment of hepatocellular carcinoma (HCC), the best prognostic index for Child–Pugh classes B and C (CP-BC) patients has not been yet established. This study aimed to elucidate the risk factors for disease-free survival (DFS) and overall survival (OS) in multicenter patients with a poor liver functional reserve after curative treatment. Methods Between April 2000 and April 2014, 212 CP-BC patients who received treatment in five high-volume centers in Japan were included in this study. CP-B and C patients were 206 and 6, respectively. Cox proportional hazard regression analyses for DFS and OS were performed to estimate the risk factors. Results The mean observation time was 1132 days. Mean Child–Pugh score and indocyanine green retention rate at 15 min were 7.5 and 31.5%, respectively. Histological chronic hepatitis and liver cirrhosis were observed in 20% and 74% patients, respectively. In the multivariate analysis, the risk factors for DFS were des-gamma-carboxy prothrombin (DCP) hazard ratio (HR), 1.6; P  = 0.012 and treatment without liver transplantation. Moreover, DCP was identified as an independent risk factor for OS (HR, 1.7; P  = 0.01). Tumor size, number, tumor thrombus, Milan criteria, liver cirrhosis, and treatment without liver transplantation were not identified as risk factors for OS. The 5-year OS in patients with high serum DCP levels (< 90 mAU/mL) was significantly better than that in those with low serum DCP levels ( P  = 0.003). Conclusions Serum DCP value before treatment predicted both DFS and OS in CP-BC patients with HCC.