This disclosure provides methods for treating a hepatocellular carcinoma (e.g., unresectable HCC) with lenvatinib or a pharmaceutically acceptable salt thereof. Also encompassed by the disclosure are dosage regimens described herein of lenvatinib or a pharmaceutically acceptable salt thereof for use in treating hepatocellular carcinoma (e.g., unresectable hepatocellular carcinoma) according to any of the methods described herein. Particularly useful dosages and dose modifications upon the occurrence of an adverse event or events are also disclosed.