Background: Lenvatinib (LEN) has been approved for patients with unresectable hepatocellular carcinoma (u-HCC) since March 2018 in Japan. We performed a retrospective nationwide multicenter study to clarify the clinical characteristics of LEN in real-world practice. Methods: A total of 343 u-HCC patients who received LEN from March 2018 to May 2020 at 23 sites in Japan were registered. Results: During the median observation period of 10.5 months, 143 patients died. In Child-Pugh A (n = 276) and Child-Pugh B (n = 67) patients, the median overall survival (OS) was 21.0 and 9.0 months. The median progression-free survival (PFS) was 8.8 months in Child-Pugh A patients. The objective response rate (ORR) and disease control rate (DCR) according to modified response evaluation criteria in solid tumors (RECIST criteria) were 42.1% and 82.1%. The independent pretreatment factors associated with mortality in all patients were AFP ≥ 400 ng/mL (hazard ratio (HR) 2.00, 95% confidential interval (95% CI) 1.08–2.09, p < 0.0001), modified albumin-bilirubin (ALBI) grade 2b or 3 (HR 1.56, 95% CI 1.09–2.17, p = 0.012), major vascular invasion (HR 1.91, 95% CI 1.26–2.89, p = 0.0022), PS > 0 (HR 1.50, 95% CI 1.09–2.08, p = 0.014), and MTT (molecular targeted therapy) experience (HR 2.22, 95% CI 1.56–3.13, p = 0.00038). In the MTT naïve patients with ALBI grade 1 or modified ALBI 2a and BCLC stage B (n = 68), median OS and PFS were 25.3 and 12.3 months. Liver-related adverse events during LEN were the only significant adverse event associated with OS (HR 2.74, 95% CI 1.93–3.88, p < 0.0001). Among the Child-Pugh A patients with extrahepatic metastasis and no major vascular invasion, median PFS in the patients with bone metastasis was significantly shorter than those with lung or adrenal grand metastasis (6.3 vs. 12.5 months, p = 0.0025). Conclusion: LEN showed a high response rate in real-world practice. Pretreatment factors, including ALBI score, AFP, and major vascular invasion are important in making a treatment strategy for patients with u-HCC. The patients with bone metastasis would be candidates for new therapeutic approaches.