Hepatitis C virus (HCV) prevails in patients with thalassemia. We aimed to investigate the efficacy, safety, and impact on red blood cells (RBC) transfusion demand of pegylated interferon (Peg-IFN)/ribavirin therapy in thalassemic patients with HCV. Methods: This retrospective study included 18 thalassemic patients (16 with HCV-1b, one HCV-1b/2b, and one HCV-2b) and 54 consecutive sex- and genotype-matched controls. Patients with HCV-2, or HCV-1 or mixed HCV-1/2 with lower viral loads plus rapid virological response (RVR) received 24-week Peg-IFN/ribavirin; whereas HCV-1 or mixed HCV-1/2 with higher viral loads or without RVR received 48-week regimens. Results: The rates of RVR, complete early virological response, and sustained virological response (SVR) in thalassemic patients were 72.2% (13/18), 94.1% (16/17), and 77.8% (14/18), which resembled those of controls (63.0%, 94.4%, and 81.5%, respectively). RVR was the only significant factor associated with SVR in thalassemic group, and was the strongest predictor for SVR among both groups (OR/95% CI = 14.7/2.20–98.6), followed by male gender and lower viral loads. More proportion of interleukin-28B-TT carriage were observed among thalassemic patients with SVR versus non-SVR (78.6% vs. 50.0%). Thalassemic patients experienced significantly less 80/80/80 adherence, more ribavirin reduction and serious adverse events than controls. Notably, there was a decreased post-treatment RBC transfusion demand versus baseline in thalassemic patients with SVR (5.21 vs. 5.64 units/month, p = 0.05), but not in those without SVR (6.33 vs. 6.56 units/month, p = 0.54). Conclusion: Peg-IFN/ribavirin was effective and tolerable for thalassemic HCV patients. Successful antiviral therapy might have extra benefit of reducing the post-treatment transfusion demand.