Conditional survival (CS) provides a prognosis of patients who have already survived several years after treatment. We investigated CS in Barcelona Clinic Liver Cancer (BCLC) stage B/C hepatocellular carcinoma (HCC) patients treated with hepatic arterial infusion chemotherapy (HAIC) with or without concurrent radiotherapy (CRT). A total of 181 patients diagnosed with HCC who were treated with HAIC with or without CRT between 2011 and 2015 were retrospectively reviewed. Overall survival (OS) and CS were calculated and a subgroup analysis was performed. The 1- and 5-year survival rates of all patients were 57.0% and 24.3%. OS was significantly higher in patients with BCLC stage B than BCLC stage C patients. Patients who achieved disease control after treatment also showed longer OS than who did not respond to treatment. Provided that the patient had already survived for 0, 1, 2, and 3 years, the CS estimates of surviving an additional 2 years were 35.6%, 55.1%, 82.0%, and 77.4%, respectively. A subgroup analysis was performed to compare BCLC stage B and C patients and revealed that CS has a tendency to increase and the difference in CS between two groups decreased over time. CS reflects the change of prognosis over time and may provide a more accurate prognosis and hopeful message to patients who have already survived with treatment.