Purpose To evaluate the feasibility, safety, and treatment effectiveness of ablative chemoembolization (ACE) in the treatment of hepatocellular carcinoma (HCC) and compare with a similar patient cohort who underwent conventional transarterial chemoembolization (cTACE). Materials and Methods This was a prospective phase I nonrandomized study conducted between March 2013 and October 2016 in accordance to the Declaration of Helsinki and Declaration Good Clinical Practice with written informed consent. There were 36 men and eight women (median age, 64 years [interquartile range, 58-74] and 74.5 years [interquartile range, 70-80], respectively). The primary end points were treatment safety and tumor response. The secondary end points were time to progression, progression-free survival, conversion to partial hepatectomy, and viable HCC within the tumor specimen. The end points of the study group (n = 22) were compared with those of a case-matched control group (n = 22) of patients who underwent conventional cTACE during the same period by using a Pearson χ2 test. Results Treatment with ACE was successfully completed in all patients without adverse effects. The complete response (CR) rates by patient or by tumor were both 100%. The median time to progression and median progression-free survival were significantly longer in the study group than in the control group (both were 28 months vs 10 months, respectively; P < .001). The number of patient conversions to hepatectomy was seven for ACE and three for cTACE. In the tumor specimens, viable tumor was found in two of eight specimens that underwent ACE and three of three that underwent cTACE. Conclusion ACE is a feasible, safe, and well-tolerated treatment for patients with HCC; it is highly effective and may be more effective than cTACE in achieving CR. © RSNA, 2017 Online supplemental material is available for this article.