Introduction Stereotactic Body Radiotherapy (SBRT) emerged as a valuable option in early to advanced-stage Hepatocellular Carcinoma (HCC) as defined by Barcelona Clinic Liver Cancer (BCLC) system. The aim of our study is to evaluate SBRT in HCC patients and to identify predictors of outcome and toxicity. Materials and methods A retrospective review of HCC patients treated at our Institution between November 2011 and December 2018 was carried out. SBRT was delivered in 3-10 fractions to a median Biologically Effective Dose (BED 10 ) of 103 Gy 10 . Results SBRT was performed in 128 patients to 217 HCC localizations, accounting for 142 treatment courses. BCLC stage was A, B, C in, respectively, 40 (31%), 72 (56%) and 16 (13%) patients. Local Control (LC), Progression Free Survival (PFS) and Overall Survival (OS) at 2 years were, respectively: 78%, 15% and 58%. LC was influenced by BED10 > 120 Gy 10 (Hazard Ratio, HR: 0.08, 95% CI 0.01–0.59; p  = 0.013) and size ≥ 3 cm (HR: 2.71, 95% CI 1.10–6.66; p  = 0.03). BCLC stage was correlated to PFS (median 14 vs 12 vs 5 months, p  = 0.012). In BCLC stage A-B disease ( n  = 112), LC was associated with improved survival (median 30 months vs not reached, p  = 0.036). Acute and late toxicity rate was 26% ( n  = 37) and 8% ( n  = 11). Patients with BCLC B-C stage disease showed increased acute toxicity (HR: 2.9, 95% CI 1.10–7.65; p  = 0.032). Conclusion Delivery of ablative doses > 120 Gy 10 and tumor size are determinants of LC. Prolonged PFS and improved OS can be obtained in BCLC A-B patients. Grade 3 liver dysfunction is infrequent.