Aims: Lenvatinib mesylate (LEN) is an orally administered tyrosine kinase inhibitor (TKI) used to treat various cancers, including hepatocellular carcinoma (HCC). LEN therapy for HCC is associated with a high incidence of adverse events, including hypertension (HTN). However, the risk factors associated with LEN therapy remain unclear. This study aimed to investigate the incidence of LEN-induced HTN (LENiHTN) and the relationship between the incidence of HTN and patient demographics in patients with HCC receiving LEN therapy. Methods: This was a single-centre, retrospective study of patients with HCC who received LEN therapy between 19 April 2018 and 30 September 2020. The observation period was from 1 week before the start to 1 month after the end of LEN administration. Results: In total, 75 patients with HCC were enrolled. LENiHTN of any grade was found in 74.7% of patients. The use of two or more antihypertensive agents before starting LEN was more common (P = 0.007); serum potassium (K), and albumin–bilirubin score (ALBI) were lower (P = 0.013 and 0.038, respectively); and albumin (Alb) was higher (P = 0.025). The cut-off values of K, Alb, and ALBI for HTN were estimated to be 4.1 mEq L-1, 3.1 g dL-1, and -1.736, respectively. In the multivariate analysis, K and ALBI were independent risk factors for LENiHTN. Conclusion: Low K and high ALBI were independent risk factors for LENiHTN. Systematic evaluation of HTN risk and early intervention for HTN prevention among high-risk patients can markedly enhance the efficacy and utilisation of LEN therapy.