Although immune checkpoint inhibitors (ICI) are used for unresectable hepatocellular carcinoma (HCC), it is unclear whether sequential ICI treatment-durvalumab plus tremelimumab (DT) after progression on atezolizumab plus bevacizumab (AB)-is effective for HCC. In this nationwide multicenter study, we aimed to investigate the effect of DT treatment based on the timing of treatment. A total of 85 patients receiving DT treatment were enrolled. The primary endpoint is treatment response at week 8 among patients receiving first-line DT treatment, those receiving second-line or later treatment without prior AB therapy, and those receiving second-line or later treatment with prior AB therapy. Objective response rates (ORRs) in patients with first-line treatment, second-line treatment without AB, and second-line treatment with prior AB were 44%, 54%, and 5%, respectively (p < 0.001). Similarly, disease control rates (DCRs) were 69%, 91%, and 26%, respectively (p < 0.001). ORR and DCR were significantly lower in patients with prior AB treatment. Progression free survival (PFS) was significantly shortened in patients receiving second-line therapy following prior AB treatment and an adjusted hazard ratio (95% confidence interval) in those patients for PFS, using first-line therapy as a reference, was 2.35 (1.1-5.1, p = 0.03). In conclusion, the impact of DT sequencing following AB treatment was limited. However, even after second-line treatment, the treatment effect can be equivalent to that of first-line treatment in cases with no history of AB treatment. Thus, prior treatment history should be taken into account when initiating DT treatment.