Hepatocellular carcinoma (HCC) is an aggressive liver tumor that occurs due to chronic liver disease, and it has a high mortality rate and limited treatment options. Immune checkpoint inhibitors have been successfully introduced and used in cancer therapy, among which inhibitors of programmed death ligand-1 (PD-L1) and its receptor programmed death-1 (PD-1) are commonly administered for HCC as combination therapy, including combined anti-angiogenic and immunotherapy combination therapy. We report a case of a primary massive HCC patient with portal hepatic vein tumor thrombus who had a good response to atezolizumab in combination with bevacizumab, following progression of disease on combined immunotherapy with pembrolizumab and lenvatinib. This case demonstrates for the first time that an HCC patient who is resistant to anti-PD-1 antibody immunotherapy can benefit from anti-PD-L1 antibody immunotherapy, providing a potentially promising strategy for the treatment of HCC.