BACKGROUND: The management of hepatocellular carcinoma (HCC) with high tumor burden and major portal vein tumor thrombosis (PVTT) remains a great challenge. The authors aimed to investigate the efficacy and safety of lenvatinib plus drug-eluting bead transarterial chemoembolization (DEB-TACE) and hepatic arterial infusion chemotherapy (HAIC) with oxaliplatin, fluorouracil and leucovorin (Len+DEB-TACE+HAIC) versus lenvatinib plus DEB-TACE (Len+DEB-TACE) for HCC greater than 7.0 cm accompanied with major PVTT. MATERIALS AND METHODS: This multicenter retrospective cohort study evaluated consecutive patients with HCC (> 7.0 cm) and major PVTT who received Len+DEB-TACE+HAIC (Len+DEB-TACE+HAIC group) or Len+DEB-TACE (Len+DEB-TACE group) between July 2019 and June 2021 from eight institutions in China. Objective response rate (ORR), time to progression (TTP), overall survival (OS), and treatment-related adverse events (TRAEs) were compared between the two groups by propensity score matching (PSM). RESULTS: A total of 205 patients were included. After PSM, 85-paired patients remained in the study cohorts. Patients in the Len+DEB-TACE+HAIC group had higher ORR (61.2% vs. 34.1%, P < 0.001), longer TTP (median, 9.8 vs. 5.9 months, P < 0.001), and prolonged OS (median, 16.7 vs. 12.5 months, P < 0.001) than those in the Len+DEB-TACE group. The ORR and TTP of both intrahepatic tumor (ORR: 64.7% vs. 36.5%, P < 0.001; median TTP: 10.7 vs. 7.0 months, P < 0.001) and PVTT (ORR: 74.1% vs. 47.1%, P < 0.001; median TTP: 17.4 vs. 7.6 months, P < 0.001) were better in the Len+DEB-TACE+HAIC group than the Len+DEB-TACE group. The frequency of grade 3-4 TRAEs in the Len+DEB-TACE+HAIC group were comparable to those in the Len+DEB-TACE group (38.8% vs. 34.1%, P = 0.524). CONCLUSION: The addition of HAIC to Len+DEB-TACE significantly improved ORR, TTP, and OS over Len+DEB-TACE with an acceptable safety profile for large HCC with major PVTT.