Background Atezolizumab plus bevacizumab showed superior progression-free and overall survival compared to sorafenib in the IMbrave150 trial. It would therefore be useful to compare the efficacy of lenvatinib and that of atezolizumab plus bevacizumab to determine if a benefit of one therapy against the other exists. Objective The aim of the present report was to apply a matching-adjusted indirect comparison (MAIC) to individual participant data (IPD) from patients treated with lenvatinib outside of randomized trials, to aggregate results derived from the IMbrave150 trial. Patients and methods Data from 455 patients who received lenvatinib as first-line systemic therapy for unresectable HCC represented the present IPD. Data inclusion were adapted to those reported in the IMbrave150 trial. Results Overall survival on atezolizumab plus bevacizumab proved to be superior to lenvatinib (log-rank: 0.001) with a hazard ratio of 0.59 (95% confidence interval 0.46–0.75). The number needed to treat ranged between seven in the first 12 months and five at the 15th month. Conclusions The present MAIC highlights that the combination of atezolizumab plus bevacizumab is superior to lenvatinib. However, updated data or sub-analyses of the IMbrave150 trial would provide more robust estimates for such a treatment comparison.